There were apparently two entrances to the courtyard. The chief of these was adjacent to the dale, and from the remains of the arch stones would appear to have been some 5 or 6 ft. wide. Here is said to have been the porter’s rooms, and if this were the main entrance, custom would place the porter there. At the other end of the wall, against the gorge, are the remains of what has been called the sally-port; but the work has been so much defaced as to render its purpose obscure. Between these two features there is a rectangular buttressed projection which may have contained rooms, while overlooking the gorge is a recess in the wall which seems to have been a window. It is said--but the statement has not been properly verified--that there are remains of the foundations of a structure which carried a drawbridge across the narrow upper end of the gorge; and it is almost certain that an ancient track leads along the hill on the further side of the gorge in the direction of the castle. All these points are of interest, and are worthy of further investigation; but that part of the ruins which most readily repays a visit is the keep. This has been described as merely a prison or a watch-tower; but from the carefully selected position of the castle, from what is known of its history, from the fact that the little town of Castleton clusters at its foot, and from a comparison with other castles, it would seem that the tower is the small keep of a small castle, and was its most secure dwelling-place. References in the great Roll of the Pipe show that a considerable number of soldiers were accommodated here; it is also recorded that in 1157 Malcolm of Scotland made his personal submission to Henry II. here, and that that king was again here in 1163, when the castle must have had even more restricted accommodation. [Illustration: 8. The Peak Castle, Derbyshire (1176.) Plans of the Keep.] [Illustration: 9. The Peak Castle, Derbyshire] The keep itself, which was built in 1176, is very similar in arrangement to the peel-towers of the Scottish border and to the towers which elsewhere formed the nucleus of many fortified houses. It probably represents the first step in domestic planning, and may be regarded as one of the earliest ancestors of the great houses of later centuries.