Old Sarum, just over a mile north of Salisbury is where four Roman roads met, which the Romans named Sorbiodunum. The massive re-cut outer ramparts and ditches of the Iron Age hillfort enclose 29 1/2 acres (11.9 hectares). The Normans added the Inner earthworks.

It was a Saxon burgh which was given military and ecclesiastical importance by the Normans to the extent that, by the start of the medieval period, the hillfort had become the basis of a town with castle, cathedral and houses, their remains can still be seen today. The ecclesiastical buildings were abandoned in the first half of the 13th century because of friction between the military and the church. A cathedral was started at New Sarum (Salisbury) and the townspeople followed. Although it was not till the Reform Act of 1832 that Old Sarum stopped returning two members to Parliament.