The _Gatehouse_ stands on the line of the curtain, projecting inwards from it, and upon the southern edge or counterscarp of the ditch of the mound. It opens into the lower ward. It is of the early Norman type, resembling that at Tickhill. It is a square of 32 feet, having in the outer and inner faces a large round-headed doorway, quite plain, without even a chamfer, and with a plain sloped abacus. The chamber is, of course, square, and but little broader than the doorways. That towards the ward seems to have been closed by a pair of doors only. The other or outer doorway has a broad portcullis groove, which may or may not be original; more probably not. The covering—the floor of the upper room—was no doubt of timber, and flat. The present vaulting is an insertion. There was always an upper floor, but this has been much altered, chiefly in the Decorated period. The old loops, now blocked, may be traced. Some of the inserted windows are very late. In the south part of the inner doorway was a door opening into a mural stair leading to the upper floor and to the rampart-walk of the curtain, which seems to have been continued through the gatehouse, over the outer portal. The present staircase is exterior, and modern. This is the whole of the original gatehouse, which, with the adjacent and very thick curtain, is probably the work of Earl Roger. The gatehouse has been extended outwardly in the Decorated period. There is appended to it a crooked passage about 10 feet broad and 40 feet long, between thick lateral walls. In its sides are shoulder-headed doorways, which led into lodges and cells, and on the south side is a well-staircase, ascending to the roof. The passage is covered by a very flat-pointed vault. It ends in an outer doorway having a drop arch, and opening between a pair of flanking towers, 20 feet square, rising out of the ditch. These have sub-basement chambers in the ditch, basements at the ground level, and two upper floors. In the doorway is a very broad portcullis groove for a timber frame, and in front was a drawbridge, now replaced by an arch of masonry. This addition to the Norman gatehouse, making with it a very long covered entrance-passage, is attributed to Earl Richard Fitz-Alan, on his return from the wars of Edward I. In very modern times the floor of the passage has been lowered about 3 feet, and the walls underpinned by a plinth. The doors which are not in use have been left unaltered, and show the original level of the sill. Probably the approach to this entrance lay through an outer gate to the north-west, at the upper part of the town, and across the large outwork, now a garden and a carpenter’s yard.