The largest settlements in the region are Newcastle upon Tyne, Middlesbrough, Sunderland, Gateshead, Darlington, Hartlepool and Durham. The region's historic importance is displayed by Northumberland's ancient castles, the two World Heritage Sites of Durham Cathedral and Durham Castle, and Hadrian's Wall, one of the frontiers of the Roman Empire. In fact, Roman archaeology can be found widely across the region and a special exhibition based around the Roman Fort of Segedunum at Wallsend and the other forts along Hadrian's Wall are complemented by the numerous artifacts that are displayed in the Great North Museum Hancock in Newcastle.