The entrance to the fortress on the north, or landward direction, was by a drawbridge across a dry moat. This was protected by two semicircular towers, and a portcullis which still exists. Above the entrance is an aperture, from which missiles and lead could be poured upon besiegers. From the gate towers a high curtain follows the formation of the rock that gradually rises to about 30 feet in height towards the south. The wall is at present mounted with ordnance used by the militia. The enclosed space is divided into two yards. The outer one, which is entered immediately from the gateway, contains a number of buildings and offices erected in 1802, at which time the castle was used as a barrack. There are also vaults, which were supposed to be bomb proof. In the line of wall is situated a small projecting tower known as the “Lion’s Den.” The inner yard is approached through a round arched gateway, and contains storehouses and keep. This latter is 90 feet high, and divided into five storeys. Its western side forms part of the outer wall. It was formerly entered by a doorway on the second floor, and a winding stone staircase in the wall of the west angle led to the top. Loopholes admitted light and air, and there was a small door at each storey. At present the ascent is made partly by wooden stairs inside. There are two towers at the summit of the keep, one on the south-east corner covering the top of the stairway, and the other at the south-west corner, which was intended for a sentry-box. On the third storey is the large room known as “Fergus’s Dining-room,” being 40 feet long by 38 feet broad and over 25 feet high. It was made into a barrack in 1793, but is now employed as an armoury. Over the chimneypiece was once a stone inscribed in Irish, which was removed in 1793. The former draw-well of the castle, 37 feet deep, was situated in the keep. It was famous for medicinal qualities. The lower portion of the building is now used as a magazine. The walls of the tower are 9 feet thick, and the corner stones, or quoins, are of yellowish limestone, which was probably quarried in the County Down on the opposite shore of the Lough. The building of the castle is generally ascribed to John de Courcy, and, although there is no direct proof that this was the case, many facts tend to support the supposition. In the first place, as De Courcy settled a colony in Carrickfergus shortly after his conquest of Ulster, it is most likely that he would provide some means for its protection. Again, it was for a long time the hereditary property of the Earls of Ulster, who were descended from De Courcy. The ancient seal of the mayor of the town bears a spread-eagle, which was the De Courcy crest, and several coins of Henry II.’s time have been found near the building. In a preface to State Papers the editors say that “the oldest fort in Ulster is Carrickfergus, built in the days of De Courcy, and never out of the possession of the English.”