Castle Mound, north of the city centre on Castle Hill, is all that remains of Cambridge's Norman castle — a substantial earth mound that was once the base of a stone keep built on William the Conqueror's orders in 1068. The castle was progressively dismantled from the 14th century onwards, and the last stone buildings were demolished in the 19th century when the mound was incorporated into a public space.
The mound is worth climbing for the views: from the top you can see across the city centre, the fens to the north, and the tower of Great St Mary's below. It is free to visit and usually quiet. The surrounding area, once the site of the castle's outer ward, is now parkland.