* The most famous section of the Great Wall of China was built between 220 and 200 BC by Qin Shi Huang, although earlier versions of the structure had existed since the 5th Century BC. The majority of this wall was ruined by the Middle Ages, but was revived by the Ming Dynasty in around 1450 AD.
* Hadrian's Wall was built around 122 AD by all three occupying Roman legions at the behest of Emperor Hadrian who believed in using frontiers to impose order in countries which had been conquered.
* The Great Wall of China is 4,000 miles long and is the longest human-made structure on the planet. But the widely-held view that it can be seen from space is actually a myth.
* Hadrian's Wall is 73.5 miles long and its exact purpose is unknown. The popular belief that it was erected to keep out the Scots has never been proven. It stretched from Segedunum at Wallsend on the Tyne to Bowness-on-Solway.