The keep has a central newel staircase, linking the basement, ground and first floors.[82] When first built, the garrison would have lived on the ground floor of the keep, the first floor being used by the captain, and the basement for stores.[83] The ground floor is subdivided by radial walls and originally would have been further subdivided by partitions; the original ovens and fireplace survive.[84] The first floor mainly dates from the 1720s, although some Tudor elements remain.[85] There is a wooden lantern structure on the top of the keep that contains a bell dating from 1655 and early 18th-century graffiti.[86] The keep's gun embrasures were converted to form sash windows in the 18th and 19th centuries.[87]