Hadrian's Wall was built by the Romans in the early 2nd century AD, stretching 73 miles from Wallsend on the Tyne to Bowness-on-Solway on the Irish Sea — the northern frontier of the entire Roman Empire. The most dramatic surviving section runs through Northumberland, where the wall follows the crest of the Whin Sill escarpment across open moorland, offering views across two countries.
The wall is a UNESCO World Heritage Site. You can walk the entire length via the Hadrian's Wall Path national trail. Key sites nearby include the fort and museum at Housesteads, and the interactive Roman Army Museum at Vindolanda. The wall was about 5 metres high, topped with 2-metre battlements, and fronted by a ditch 9 metres wide and 3 metres deep.