A circular shell keep, across, was constructed on the motte in the 12th century, complete with a gateway; that was later replaced, and the current entrance dates from the 13th century. Rising up through the keep is the 13th-century high tower, in diameter, constructed from dark shale. This replaced any internal rooms that the shell keep might have had, instead creating a small, cramped and unlit chamber at the base of the keep. The upper chamber of the high tower was fitted with a large window and a fireplace, overlooking the deer park, and archaeologist Oliver Creighton suggests the tower was intended to be used a "private grandstand", with the parapet below being used for other forms of "lordly display" over the local community. The tower now leans slightly.