Throughout history, various communities and civilisations have constructed barriers between themselves and others.

So here is a look at those historical constructions.


This is one which is practically forgotten about today;
The wire of death or Dodendraad, to give it it's Dutch name. This was a an electrified fence constructed by the Germans during the First World War along the Dutch-Belgian border.

Between 2 and 3 thousand people were killed attempting to cross the frontier during the war years.

http://www.dodendraad.org/index.php/wire-of-death



the wire near Sluys;

Commonly believed to be the only man-made object which can be viewed from space, though no-one has ever actually done so, the Great Wall of China, is most certainly an impressive construction.

The Wall, perhaps more accurately, Walls, have a history going back to the Qin Dynasty of the 3rd century BC and were maintained, repaired and extended throughout Chinese history;

http://en.wikipedia.org/wiki/History_of_the_Great_Wall_of_China

How it was Made.

In the Qin dynasty, the wall was made by certain methods. The laborers would put a thick layer of raw earth on the bottom. This was used as a foundation of sorts. On top of that they would put a layer of silt and clay known as loess. After this foundation had been built, rammed earth was used to build up the wall.




In order to make the rammed earth for the wall, laborers would fill a wooden frame full of dirt and place it on the foundation. Than they would smash it down until it was very compact. That would be one thin layer of compact earth. They would place each layer on top of the last. Stone fragments and other debris were added as well to try and strengthen the wall.
It was a long process.


The Ming dynasty had different methods of building the Great Wall. They had better technology such as kilns to make strong bricks for building. They would build the wall by constructing rammed earth and using it as the innermost layer of the wall. They would then use bricks and stone on the outer layer by methodically placing them together. They had a special mortar for the bricks that was made of rice and lime.

This method made a wall that was many times stronger.

What was the great wall of china built out of?

Building the Great Wall was a tremendous effort. Trying to send materials from anyplace that wasn't local was too much of a hassle. Depending on the landscape, the materials of the wall would change accordingly to decrease transportation problems.


If the wall was going through a mountain, stones from that same mountain would be used as materials for the wall. If the wall was passing through plains, rammed earth would be used.
When the wall passed through the desert, the materials used were juniper tamarisks and sanded reeds.


The materials used when the Great Wall was first built were mostly rammed earth and loess since weapon technology wasn't very advanced.
The Ming dynasty brought with it new, stronger materials for the Great Wall. They used bricks, stone slabs and lime.

Offa's Dyke has always fascinated me. Its function as anything other than simply a "line in the sand" between Mercia and Powys is unknowable. Too easy to traverse, too long to effectively patrol, it could never have acted as an effective military barrier, and yet the most recent archaeological evidence suggests a construction continually added to and repaired over three centuries. The labour involved must have been immense. Even more interestingly, although it was most certainly a Mercian innovation, it seems that some of the improvement/repairs were initiated from the Welsh side. Its proximity to the political border between modern England and Wales makes it proof of one of the longest enduring borders that haven't shifted in world history.

The first one that has come to my mind is the Rabbit-Proof Fence in Australia made famous by a film of that name.  Wikipedia tells me it was the longest unbroken fence in the world (over 1800 kms long) when it was erected in 1907 to keep rabbits in check extending to over 3500kms overall with the addition of two other fences, and was checked by a variety of methods including riding on camels round it.  It says when myxomotosis was introduced in the 1950s the need for it reduced.  But farmers illegally introduced myxomotosis into NZ some 15 or so years ago, and although it had some immediate impact it hasn't lasted.  And an annual single weekend rabbit hunt at Alexandra nets about 20,000 rabbits (from memory).

Often overlooked by the more famous Hadrian's Wall to the south, the Antonine Wall marked the North-West Frontier of the Roman Empire;

http://www.antoninewall.org/

Great semi-visible wall :

http://www.universetoday.com/25364/can-you-see-the-great-wall-of-china-from-space/

The Berlin Wall, built by the East German government to prevent it's citizens moving to the west.

Construction began in August 1961;

This isn't Berlin, but Oxford. The Cutteslowe Walls built to separate a private housing estate from the council estate next door;

Part of the Zuiderzee works in the Netherlands, the Afsluitdijk separates the North Sea from the new freshwater lake the Ijsselmeer.

http://en.wikipedia.org/wiki/Afsluitdijk



The centuries old Dutch battle against the sea, the Zuiderzee works have created new land for the Netherlands;

Caro wrote:

The first one that has come to my mind is the Rabbit-Proof Fence in Australia made famous by a film of that name.  Wikipedia tells me it was the longest unbroken fence in the world (over 1800 kms long) when it was erected in 1907 to keep rabbits in check extending to over 3500kms overall with the addition of two other fences, and was checked by a variety of methods including riding on camels round it.  It says when myxomotosis was introduced in the 1950s the need for it reduced.  But farmers illegally introduced myxomotosis into NZ some 15 or so years ago, and although it had some immediate impact it hasn't lasted.  And an annual single weekend rabbit hunt at Alexandra nets about 20,000 rabbits (from memory).

It may have kept the rabbits out but the rabbitproof fence caused its own set of problems to other wildlife though. Largely by not allowing kangaroos (who naturally travel long distances) and other species to move to new pastures which caused massive overgrazing in some areas. Also in times of drought (a common occurance in Australia) the restriction of the fence was effectively a death sentence for a great many animals, once again because it didn't allow them to travel into less drought stricken areas in search of food and water.

Couldn't not post something about Hadrian's Wall;

http://www.odysseyadventures.ca/articles/hadrian-wall/article_hadrianswall-thewall.htm

Islanddawn wrote:

Caro wrote:

The first one that has come to my mind is the Rabbit-Proof Fence in Australia made famous by a film of that name.  Wikipedia tells me it was the longest unbroken fence in the world (over 1800 kms long) when it was erected in 1907 to keep rabbits in check extending to over 3500kms overall with the addition of two other fences, and was checked by a variety of methods including riding on camels round it.  It says when myxomotosis was introduced in the 1950s the need for it reduced.  But farmers illegally introduced myxomotosis into NZ some 15 or so years ago, and although it had some immediate impact it hasn't lasted.  And an annual single weekend rabbit hunt at Alexandra nets about 20,000 rabbits (from memory).

It may have kept the rabbits out but the rabbitproof fence caused its own set of problems to other wildlife though. Largely by not allowing kangaroos (who naturally travel long distances) and other species to move to new pastures which caused massive overgrazing in some areas. Also in times of drought (a common occurance in Australia) the restriction of the fence was effectively a death sentence for a great many animals, once again because it didn't allow them to travel into less drought stricken areas in search of food and water.

I know it's a serious subject, but;

In more modern times, the Gaza wall



All these great walls through history that were designed to keep others out for one reason or another and they do eventually all come down. An excercise in futility?

Not forgetting the brilliant polygonal walls of the Inca

And also the so-called 'Long Walls' defensively linking the ancient city of Athens to its vital port and naval base at Piraeus.

You beat me to it MM, I was just looking for an image of the Athenian Walls. So here it is.

You beat me to it ID.

So then how about also Homer's "Tiryns of the strong walls", supposedly built by the Cyclops.

.... although I'm now sliding towards purely defensive walled fortifications rather than, as I think Trike intended, walls as boundaries. Sorry.

Meles meles wrote:

You beat me to it ID.

So then how about also Homer's "Tiryns of the strong walls", supposedly built by the Cyclops.

I was just looking at the same! Great minds think alike, as they say.

I'm just chuffed I can still remember some Homer!

He pinched that line - "Uruk of the Strong Walls" in the Enmerkar/Lugalbanda/Gilgamesh legends predates Homer

From 1912 to 1913, Julius Jordan and his team from the German Oriental Society discovered the temple of Ishtar, one of four known temples located at the site. The temples at Uruk were quite remarkable as they were constructed with brick and adorned with colorful mosaics. Jordan also discovered part of the city wall. It was later discovered that this 40 to 50-foot (15 m) high brick wall, probably utilized as a defense mechanism, totally encompassed the city at a length of 9 km (5.6 mi). Utilizing sedimentary strata dating techniques, this wall is estimated to have been erected around 3000 BC.

How about Ulster?

The Roman Walls of Lugo, Spain

Triceratops wrote:

Part of the Zuiderzee works in the Netherlands, the Afsluitdijk separates the North Sea from the new freshwater lake the Ijsselmeer.

http://en.wikipedia.org/wiki/Afsluitdijk

According to the Scientific American, that IS visible from low-earth orbit.

Gilgamesh of Uruk wrote:

According to the Scientific American, that IS visible from low-earth orbit.

And one of the Seven Wonders of the Modern World.


Re fortified sites, I would say it is fair to include them. And these go back right to the start of Human Civilisation.

The proto-city of Jericho circa 8000 BC (from wiki)

Perhaps the most important discovery was evidence that the earliest wall suggested by Kenyon to date to around 8000 BC based on Radiocarbon dating of material at 7825 BC from level IV, phase III of the site. This time period was thereafter called the Pre-Pottery Neolithic A stone age and the wall considered part of an early proto-city It surrounded and protected a Neolithic settlement which contained an organized community of between 2,000 to 3,000 people.

The wall was complemented by a stone tower built into it. The wall is thought to have been built in order to prevent floods and the tower used for ceremonial purposes but the height of the wall (approximately 1.5 metres (5 ft) thick and 3.7 to 5.2 metres (12 to 17 ft) high) as well as that of the tower suggests a defensive purpose as well.

A restored section of the Theodosian Wall of Constantinople;

nordmann wrote:

Offa's Dyke has always fascinated me. Its function as anything other than simply a "line in the sand" between Mercia and Powys is unknowable. Too easy to traverse, too long to effectively patrol, it could never have acted as an effective military barrier, and yet the most recent archaeological evidence suggests a construction continually added to and repaired over three centuries. The labour involved must have been immense. Even more interestingly, although it was most certainly a Mercian innovation, it seems that some of the improvement/repairs were initiated from the Welsh side. Its proximity to the political border between modern England and Wales makes it proof of one of the longest enduring borders that haven't shifted in world history.

According to the two decades long study conducted by the Offa`s Dyke Project, led by Margaret Worthington and the late David Hill of Manchester University, the great barrier was indeed military in function, always facing west, and would have been a formidable obstacle. They also concluded that the actual section of the dyke built by Offa would have been 64 miles in length only and built to deter attacks from the Welsh kingdom of Powys.

Hi Aelfwine. Its military role is the most enigmatic feature of the construction, particularly given its provable longevity had it retained that role throughout - long outliving its creators as it did. As a purely geographical feature without considerable military presence along its length it would have been of negligible worth, a fact that would appear to make the huge expenditure and investment in its construction and upkeep almost incomprehensible. Yet on the other hand the presumed militarisation of the structure (over 300 years) calls into question the population and demographic dispersion as estimated from other archaeological evidences from the surrounding area during this long period.

As an effective deterrent to attacks from Powys, which is a rather logical deduction to arrive at for its intended purpose at least originally, it therefore serves to highlight just how little we can presume to know regarding contemporary Mercia (and Powys). That it was maintained over many generations should tell us everything we need to know regarding how these two states viewed each other, and yet instead it simply serves to contradict much of what we have learnt about this relationship from other reliable sources.

That is what I meant by "unknowable". It is very hard to imagine an historical context in which all the data makes total sense, and the biggest fly in the historical ointment is the indisputably gargantuan construction that, of all the extant archaeological data, is the one which is by far the most impossible to ignore.

Well Nordmann, Offa`s predecessor as king of the Mercians was Aethelbald 716-757, a formidable king who exercised some form of hegemony over Powys, and this lasted until he was murdered by his bodyguards at Seckington, a village four miles from Tamworth. A civil war ensued between two rival aethelings, Offa and a shadowy figure called Beornred, seemingly from a rival dynasty. This Mercian civil war coincided with the rise to power of a powerful and aggressive Welsh king in Powys, Eliseg, who took advantage of the chaos in Mercia, recovered some territory lost to the Mercians, and launched raids into Mercia itself. Eventually, however, Offa saw off his rival, consolidated his rule in Mercia, and then turned his attention to Powys, conducting at least two successful campaigns there and thus stabilising the frontier. It was after these campaigns that he seemingly built his great dyke, perhaps as an "overkill", and perhaps as a grand show of prestige. Indeed, after its construction it was never repaired mainly because the power of Powys went into rapid decline.

Thanks Aelfwine. In April this year the findings of a Clwyd-Powys Archaeological Trust excavation pointed to the 95% probability that the dyke predated Offa by two whole centuries, at least in part! The same Trust some years ago also found evidence that some substantial portions of the dyke reinforced with quarried stone had used material originating in Powys, and that one of these portions was likely commensurate with the period just after Offa's reign, indicating a repair or revampment initiated from the Powys side in a period when one would have assumed the dyke's principal role as a defence against them was still viable. This is why the dyke throws up as many questions about the Powys/Mercia situation throughout the period that included Offa as it answers, I feel. Especially if the answer to any question is simply "Offa built it".

The erroneously named Danes Dyke at Flamborough Head, East Yorkishire.



The Dyke actually dates back to the Bronze Age.

And perhaps Britain's most recent defensive dyke, the Scots' Dyke separating "The Debatable Lands" from civilisation  

This one has already had a mention on "The Norsemen" thread, The Danewerke across the Jutland peninsula;

I recall that, in the dear, dead, days of the BBC message board, extended discussion of the function of Hadrian's Wall - defensive structure, forward operating base, custom's barrier, vanity project, power statement, identity marker etc, etc - and all of these structures, frontiers and boundaries are open to the same kind of analysis. Offa's Dyke seems to me, and forgive me for knowing sweet f.a. about it but that's never stopped me before, to be particularly suitable for that kind of
examination/speculation/theoretical interpretation. Given its apparently long life, it might also be a mistake to attribute an unchanging function to such a construction, what starts as fulfilling a particular role can, often, over time acquire a quite different significance and be understood at different periods to represent many things. There's a comparison with the appropriation of other types of antiquities, particularly those of the neolithic, bronze age and iron age, by later societies as signifiers of more abstract and ideological ideas.
The sheer scale of the feature, implying as it does mass community involvement in its construction and later maintenance, also makes me consider some of the theories that place the process of building large scale monuments as at least as important as the final product in creating and maintaining societal cohesion and identity formation.

This is part 1 of 3 of an archaeology blog about the construction of Hadrian's Wall;

http://structuralarchaeology.blogspot.co.uk/2012/01/hadrians-first-wall-part-1-of-3.html

Triceratops,

read the site...and found it yet another theory...you know me always seeking for the "about us" or the sources...
https://www.ocs.soton.ac.uk/index.php/CAA/2012/paper/view/682
http://archaeologynewsnetwork.blogspot.be/2011/01/archaeologist-claims-vallum-was.html#.VCmqosIcQdV
http://structuralarchaeology.blogspot.be/2009/06/30-not-going-with-flow.html

From the last http:

So who am I?


I am the archaeologist who came in from the cold, chilled world of commercial server rooms, bringing with me nearly twenty years of research. I sought shelter in my local university, only to find that my knowledge is of no value, because I have no value -- I do not attract funding -- I am worthless. Which is pretty much how I was treated; it’s not that they did not believe or understand theoretical structural archaeology -- they could not even be bothered to listen, even after I gave them all my money, so I hit upon blogging as the only way forward for my research. This way I get a self-selecting audience, who are most welcome to join in and comment, and no money changes hands.


Thus, Theoretical Structural Archaeology occupies a strange space beyond the academic firewall, your host is a worthless individual, and nobody has been paid to check that I’m not lying to you, and so you're just going to have to use your own judgment, which, as I said earlier, is actually the whole point.




Kind regards and with esteem,

Paul.

ferval wrote:

I recall that, in the dear, dead, days of the BBC message board, extended discussion of the function of Hadrian's Wall - defensive structure, forward operating base, custom's barrier, vanity project, power statement, identity marker etc, etc - and all of these structures, frontiers and boundaries are open to the same kind of analysis. Offa's Dyke seems to me, and forgive me for knowing sweet f.a. about it but that's never stopped me before, to be particularly suitable for that kind of
examination/speculation/theoretical interpretation. Given its apparently long life, it might also be a mistake to attribute an unchanging function to such a construction, what starts as fulfilling a particular role can, often, over time acquire a quite different significance and be understood at different periods to represent many things. There's a comparison with the appropriation of other types of antiquities, particularly those of the neolithic, bronze age and iron age, by later societies as signifiers of more abstract and ideological ideas.
The sheer scale of the feature, implying as it does mass community involvement in its construction and later maintenance, also makes me consider some of the theories that place the process of building large scale monuments as at least as important as the final product in creating and maintaining societal cohesion and identity formation.

Ferval,

I recall the long discussion too on the ex-BBC messageboard.

"Given its apparently long life, it might also be a mistake to attribute an unchanging function to such a construction, what starts as fulfilling a particular role can, often, over time acquire a quite different significance and be understood at different periods to represent many things. There's a comparison with the appropriation of other types of antiquities, particularly those of the neolithic, bronze age and iron age, by later societies as signifiers of more abstract and ideological ideas.
The sheer scale of the feature, implying as it does mass community involvement in its construction and later maintenance, also makes me consider some of the theories that place the process of building large scale monuments as at least as important as the final product in creating and maintaining societal cohesion and identity formation."

I am always happily surprized by your insightful thoughts and well written messages. We have not only Nordmann...

Kind regards and with esteem,

Paul.

The Maginot Line along the French frontier with Germany. Not so much a line as a deep zone of bunkers, block-houses, artillery casements, fortresses, tank traps, barracks and supply dumps, all linked by a narrow-guage underground rail system. The First World War had demonstrated the effectiveness of defensive combat (as well as showing how to overcome it) and this clearly influenced French military thinking. The resulting Maginot Line was extolled as a work of genius which it was believed would prevent any further invasions from the east. As a purely static defensive line it did protect France from direct attack, but ironically by tying up considerable numbers of men and equipment in fixed positions, it served as much to protect Germany.

Strategically it was completely ineffective. Initially it only extended from Switzerland to Luxembourg - Belgium was after all France's ally. When in 1934 Belgium opted for neutrality hasty attempts were made to extend the line along the Franco-Belgian frontier to the Channel coast but by 1940 these extensions were far from complete. Furthermore the fortifications did not extend through the Ardennes which Gamelin, French Commander-in-Chief, believed to be impenetrable. In the event of course the German invasion, when it came, drove straight through the 'impenetrable' Ardennes while simultaneously advancing through Belgium, simply bypassing the end of the Maginot Line and Belgium's own system of fixed forts.

Meles meles,

there you bring up a point...I think I read already more than thousand pages about the question on different French fora and contributed also some 100 till 200 pages...
The big mistake was, and there seems to be some unanimity about it, the advance of the first French army into Belgium in the direction of the Dutch Breda...they had better stayed together with the British along the Belgian border; also the advance of the French into the Belgian Ardennes was also badly coordinated with the Belgian army...
I made a what if with the push through the Ardennes stopped and a broad front together with the British to the middle of France...there was nevertheless an allied defeat due to the bad organized French army but there was a retreat to AFN and no Pétain, no Mersh el kebir...but it would have been quite another war and with an even perhaps quite other outcome than de battle of Britain...

Kind regards and with esteem,

Paul.

PS: I was and still am on a French Napoleonist forum, whose owner wants to check the Napoleon corpse in the Dôme des Invalides to see if it is not another one that the British have put in the sarcophage:

http://www.empereurperdu.com/forum/phpBB2/index.php

He started also a new forum of history where I, together with another French language Belgian, contributed a lot. Attacked by the leader of the forum BRH about the annulment? (French:annulation) of the French Belgian military treaty in 1934 I did in depth research how that event developped...posted  also on that forum a lot of messages concerning the German invasion of Belgium and France in May 1940...
http://www.empereurperdu.com/tribunehistoire/

Kind regards and with esteem,

Paul.

I have just finished reading Simon Armitage's book on walking the Pennine Way (to be recommended, I might say). On one page he talks of Hadrian's Wall. He said, "As a declaraton of territoriality and power, it takes some beating, but like all such barriers and attempted delineations, be in the Iron Curtain, Offa's Dyke, the Berlin Wall, or the US-Mexican border, it is in the end a shrine to failure. Holding back or penning in human populations is like trying to fence off the weather, and as much a statement of insecurity as one of power.  As determined as it is to divide and exclude, a wall is there to be climbed over or knocked down, and the bigger the wall, the greater the challenge...Hadrian's Wall, for all its formidable dimensions, was destined to become nothing more than a line in the sand, a monument to a grand but doomed vision worthy of Ozymandias."

Have any succeeded in their original intentions?

The judgement on Hadrian's Wall seems a trifle harsh. Its function over most of its existence seems to have been less a military bulwark against invasion from the north and probably much more a very definite line of demarcation between two spheres of trade and government. In any case we have no record of any major battles fought in its vicinity, indicating that it served its military and political purpose well and fell out of commission only when the entire political structure south of it was suddenly abandoned in the 4th century. Other speculation that its original primary function was to divide and thereby neutralise the Brigantes is supported also by the fact that this once powerful northern power centre of tribal alliances effectively disappeared from history after the wall's construction - another success if this is the case. As a trade regulator set up to protect and encourage the growth of wealth on its Roman side the evidence points to even more success for the wall, the archaeology tending to confirm a consistently higher standard of living on its southern side. So yes, it could be considered a rather impressively constructed monument to the ultimate failure of Rome to hold on to its British possessions, but not a failure in its own right, I would tend to argue. It did what it was designed to do for as long as those interested in keeping it going kept it going.

I'd suggest that the Wall was a success in its role as the material embodiment of an idea, a concrete expression of Romanitas, then and to this day. If being Roman, being different and superior to those outwith, mattered then there had to be a boundary, there couldn't just a peetering out, a place where the Roman world just gradually faded into the barbarian other. With walls, as with houses, the gates and doors are as important as the barriers and who is allowed entry and who is excluded defines those within as well as those without.

I sometimes play with the question, had our own peerie wall been held and enhanced, would the history of these nations been any different? Would the experience of being Roman and the change that would have made to our respective national mythologies radically changed the mind set of the lands between the walls?

One wall that failed (and failed, and failed) was the so-called "Long Wall of Thrace", otherwise known as the "Anastasian Wall". Erected in the late 5th century it was designed to keep the barbarian hordes out of Constantinople's hinterlands to its northern side. However from the moment of its inception it appears instead to have acted as a sort of magnet to the same hordes (the word "horde" here being used in its original sense - as first applied by the Byzantines to the "Tyrcae" - or as we would call them "Turks" - and then to anyone else who ganged up in large numbers on their municipal borders).

The Anastasian Wall was evidently first built to withstand the Huns. They over-ran it easily however (several times) and under Attila even had the audacity to take over the running of it - effectively using it as a blockade starving Constantinople of trade imports overland and charging the city a fee to let things through. After Attila's death the empire took it back and fortified it further - a bad move as that only then made it attractive to the Slavs, a recently arrived group who realised that it might be a good idea to proactively shut out potential military expeditions from the Eastern Roman Empire headquarters which might hinder their colonisation of Illyria in the vacuum the Huns had left behind them. The Byzantines' own wall proved very handy indeed for that purpose.

Once the Slavs' use for the wall was over and they had managed to ensconce themselves to the extent that they would never be budged again the Byzantines, now attempting to ensure that the Slavs didn't attempt to ensconce themselves even more, elected to commandeer their own wall back and extend its fortifications even further than the Slavs had. So well did they do this that another "new" people, the Bulgars, realised that this structure would make a perfect launch pad for their armies in wars against the Slavs, whose recently acquired land they were now themselves encroaching upon. On occasion they even used it to launch attacks on Constantinople itself.



By the 7th century it was clear even to the dimmest Byzantine emperor (a title hotly contested by several claimants) that the "Long Wall of Thrace" was more of a liability than a defence mechanism. They abandoned it - though not without first paying a hefty ransom to the Bulgars - and apparently agreed amongst themselves never to mention it again. So effective was this agreement that today this amazing structure - second only to Hadrian's Wall in terms of Roman military mural defence lines - is almost totally forgotten. Over the centuries large chunks of it completely disappeared as its well-cut stone infrastructure proved invaluable for re-use in surrounding buildings, and today only glimpses of its former majesty can be obtained in wooded mountainous regions around its northern extremity.





Between 1994 and 2000 the University of Edinburgh conducted a project aimed at documenting what's left of the "Long Wall" and at devising a conservation plan for its scant remains, some of which they discovered actually pre-dated the emperor Anastasius I (so the popular name for the wall is wrong) and instead appear to have been first commissioned during the earlier reign of Zeno (he who murdered his own son Leo to take the throne and then blamed the lad's mother - not a nice chappy at all).

This must be one of the oldest.
http://www.orkneyjar.com/archaeology/nessofbrodgar/excavation-background-2/the-great-wall-of-brodgar/

I'd take the "Atlantis" bit of this http://www.atlantisquest.com/Archeology.html with a megalith of salt - but some interesting walls in it.

Another underexamined wall, or walls, is Trajan's Rampart in Romania, running from the Black Sea to the Danube. This complex of three walls had been traditionally accepted as dating from the days of Roman Dacia and this was supported by excavations in the late 19th c. but the discovery, during building works in the 50's, of a slab with a Slavic inscription referring to events in the 10th c., led to it being redated and subsequently largely ignored.


                                                                   

This has now been questioned following a recent aerial archaeological survey of the area, satellite images  and by the analysis of archived RAF and Luftwaffe aerial photographs from WW 2.

                                       
It would now appear that these walls are at least in part indeed Roman but modified for reuse later, including 'turning' them to face threat from the opposite direction.


http://www.ecusd7.org/ehs/ehsstaff/jparkin/Academics/Ancient_World_History/Flowering_of_Civilizations/Han-Rome_Comparison/Rome/Roman_Military/Army/Valu_lui_Traian-Rediscovering_a_lost_Roman_Frontier.pdf

Hadrian's Wall is to get a new discovery centre;

http://www.bbc.co.uk/news/uk-england-tyne-31088558

The Atlantic Wall ultimately failed, of course, but it was still a formidable barrier. The Channel Islands were its strongest bastion, with 10% of all steel and concrete used in the entire Wall allocated to the Islands; indeed it's been said they were better defended than the Normandy beaches. The fortifications were never completed, but it's a mark of how physically strong they were that most still stand today - the authorities post-War simply gave up trying to demolish them! The anti-tank walls on the beaches still do excellent service as sea walls.

And well behind the Atlantic Wall was the so-called "Westwall", a German defensive line, much further east along Germany's western frontier, whose construction was started during the 1930s to oppose French Maginot Line. By 1940 it was far from complete and once France was occupied, all work stopped.

But after D-Day construction was rapidly restarted. Too late, and the frantic attempts to build a second  "Siegfried Line" probably only served to drain manpower from other, more essential war-work. The project was never completed before it was over-run and by-passed by the Allies' advance in May 1945.

But huge stretches still exist completely untouched. Being too expensive to demolish, the most complete stretches have been declared nature reserves ... and so the old fortifications have now become the preserve of wildlife.

http://en.wikipedia.org/wiki/Inland_Customs_Line

Read Roy Moxham's book "The Great Hedge of India". An odd sort of book more or less about an odd sort of barrier.

The "Siegfried Line" fortifications in the Hurtgen Forest on the Belgian-German border were the scene of a bloody, and nowadays largely forgotten, battle in the Autumn of 1944;

photo of German bunker in the Hurtgen;