side of the keep. The Captain's House occupies the western side of the courtyard, and the Governor's Garden lies beyond the eastern wall. The castle is entered through an outer gateway on the southern side, surmounted by Charles II's coat of arms. When first built, the castle would have held three tiers of artillery, two in the front battery and a third layer in the central tower. The keep was originally protected by a moat, since filled in, with a drawbridge, of which only the slots now survive. The castle could have been protected at short-range with hand guns, although the gunloops for these were of an antiquated design for the period, and a moated earthwork, , was subsequently built to the rear of the castle to provide additional protection. The keep is two storeys high, built of ashlar Portland stone. Historic England considers it to form "one of the best preserved and best known examples" of the Henrician forts. In the centre of the ground floor is the octagonal great hall, now fitted with large Victorian windows, which would have originally providing living space for the garrison. Off the great hall are wings holding the gunners' quarters and the castle's kitchen, the latter equipped with a large, 16th-century fireplace. Running around the front of the keep is the gun room. This was originally a two-storey gun battery with embrasures for five guns on the ground floor and four more above on the first floor, with the southern end of the ground floor subdivided into four barrack rooms. The ground-floor embrasures were designed with vents to allow the smoke from the guns to escape. Both the wooden roof that formed the first-floor gun platform and the internal wooden partitions have been dismantled, however, and the chamber is now open to the air. It now houses a variety of 18th and 19th century cannons. On the first floor is the upper hall and the captain's chamber, used in the 16th century as a living and working space by the castle's commander, and converted into a dining room and a bedroom in the 19th century. On the opposite side to the captain's private chamber are two other bedrooms, possibly originally for the use of the castle's lieutenant. The current Governor's Garden was created in 2002 by the horticulturist Christopher Bradley-Hole, as part of a wider programme of work across English Heritage properties.