Hadrian's Wall. The wall was built from around AD 122 at the order of the Roman Emperor Hadrian. After completion it was a total length of 117,000 meters, extending from Segedunum at Wallsend on the River Tyne to the shore of the Solway Firth. Its purpose was to defend Roman Britain from the Picts, a group of tribes from northern Scotland and other enemies from conquered lands. The remaining wall is a popular tourist attraction and a World Heritage Site. Cumbria, England.