Carlisle Castle was possibly a late 11th century earth and timber ringwork, founded by King William II. Standing with a natural slope to the north and built in part of Luguvalium Roman Fort, a deep ditch gave defence to the south. In 1122 King Henry I visited Carlisle and ordered that it be fortified with a stone castle and towers. In the large outer ward are 19th-20th century barracks and a raised parade ground, which gives the mid 16th century half-moon battery guarding the inner gatehouse an odd look. In the smaller inner ward, is a massive 12th century three storey keep, originally entered from a forebuilding and the remains of an Elizabethan range, with an octagonal stair turret. The castle has been continuously occupied since its foundation and is the most frequently besieged place in the British Isles. 4 miles north-west is Beaumont Motte and 6 miles east is Corby Castle