Around AD 74–79 the Roman army built a legionary fortress, Deva Victrix, on a sandstone bluff above the River Dee to house the XX Valeria Victrix legion. Its playing-card-shaped defensive circuit — four straight walls, four main gates, and a street grid pivoting on the via principalis and via praetoria — still dictates the layout of the streets inside Chester's walls today.
Chester's is the most complete Roman and medieval defensive circuit in Britain — you can still walk almost the entire two miles on the wall-walk itself, passing the Eastgate clock, the Water Tower and the Roman amphitheatre just outside the southeast corner.
A 3D model of the Roman legionary fortress of Deva Victrix beneath modern Chester, with a walkable reconstruction of the city walls and a toggle between the original Roman circuit and the larger medieval one built over it.
On the north and east sides the medieval walls were rebuilt directly on the Roman fortress line; on the south and west they were pushed outward toward the River Dee, roughly doubling the enclosed area as the town outgrew the legionary camp.
Switch the era layer, set a walk speed for the patrolling sentry, and toggle follow-camera to ride the wall-walk yourself. Sweep the time-of-day slider to watch the sun move over the Dee valley.
Chester's walls form the most complete Roman and medieval defensive circuit in Britain — nearly the full two miles can still be walked today along the original wall-walk.