Old Sarum was initially a hill fort strategically situated on the conjunction of two trade routes and the River Avon, Hampshire. The Romans established a camp here named Sorviodonum. Cynric, king of Wessex, was said to have captured the place in 552.
After the Norman Conquest, the town was renamed Salisberie after the Earl who received the area. He built a wooden castle with a ditch, and in 1067 started a cathedral. He completed it in 1092 (it burned down five days later), and in 1100 built a stone keep. A replacement cathedral was completed in 1190.
But space ran out on the hilltop, with cathedral and castle sitting cheek by jowl and their respective chiefs in regular conflict; so in 1219 the bishop started construction on a new cathedral on the banks of the Avon. A new settlement grew up around this, called New Sarum, and eventually the name of Salisbury was used only for the new town. Old Sarum was slowly abandoned and fell into ruin. Not much is still standing there, but visitors may easily trace the outlines of the old castle and cathedral.
From mediaeval times Old Sarum elected two members to the House of Commons, despite the fact that from at least the 17th century it had no resident voters at all. In 1831 it had eleven voters, all of whom were landowners who lived elsewhere. This made Old Sarum the most notorious of the rotten boroughs of the pre-1832 House of Commons. The Reform Act of that year deprived Old Sarum of both its seats.
Old Sarum's long history makes it a popular location for historical reenactments.
Old Sarum by John Constable, 1829