Under Henry II, the Castle was totally rebuilt, and the walls of the inner bailey and the eastern part of the outer curtain wall erected. Most impressive is the monumental keep, built by Henry II's great architect, Maurice the Engineer, between 1180 and 1185, which stands at the heart of a concentric ring of defences.The keep, or Great Tower, is 83 feet (25.3m) high and just under 100 feet (30m) square, with walls up to 21 feet (6.5m) thick. It dominates the inner bailey giving an overwhelming feeling of strength and power.The keep was designed to serve many functions: as a storeroom, occasional residence of the monarch and his court, and perhaps most importantly, as a stronghold. Throughout, the internal arrangement of the keep is ingeniously designed. Its three-towered fore-building, carrying the entry staircase and two chapels, is an elaborate and magnificent approach to the main apartments. The upper chapel, richly decorated and reserved for the royal family's use, is especially fine. The former royal apartments are still impressive in their monumental scale, despite having lost most of their original decoration.Recently the interior of Henry’s Great Tower has been recreated. Historians, designers, artists and craftspeople have combined to present it as it might have appeared when newly completed, and ready to receive an important visitor, Count Philip of Flanders, in 1184.