Exeter's Roman and medieval city walls survive better than almost any other English city. The circuit is largely intact and can be walked in sections throughout the centre, with the best-preserved stretches on the north and east sides near Northernhay Gardens and along Southernhay.
The walls were originally built by the Romans around 200 AD in red volcanic trap stone, standing some five metres high. Medieval builders later raised and repaired them, and in places you can clearly see the layers: Roman stonework at the base, medieval additions above. The section beside Athelstan's Tower on the north side is particularly well preserved.
Northernhay Gardens, running along the outer base of the north wall, is England's oldest public open space (opened 1612) and provides the best vantage point for the wall's full height. The Rougemont Castle gatehouse at the north end dates from 1068 — built by William the Conqueror within weeks of the city's submission after the Siege of Exeter.