The curtain walls at Trim, two-thirds of which still stand, had a perimeter of 500 yards. They must have been completed by 1224 when William Marshall, the justiciar, besieged the castle for seven weeks, for it is unlikely the castle could have withstood his army for such a period without the protection of the curtain walls. The remains now consist of two sections, the first comprising the west gatehouse and the wall from it to the northern tower, while the second comprises the vulnerable southern curtain with its five D-shaped towers and circular east gatehouse.
It has been argued that the rectangular west gatehouse is earlier because its vaulted passage uses round, rather than pointed, arches, but this is conjectural. There appears to have been a barbican on the town side of the west entrance, which was further protected by a murder hole, a portcullis, the gate, and a second murder hole through a hole in the passage. Barbicans only rarely survive, but the east gatehouse entrance passage is continued outwards between two crenellated walls to a fine barbican on the outer edge of the moat. It is often claimed that the upper rooms of this gatehouse were used to house the young Prince Hal, later Henry V, who was left at Trim by Richard II in 1399 before his fateful return to England.
An extensive excavation was carried out between 1971 and 1974 in the area between the keep and the south curtain wall. This revealed a stone plinth added to the keep, parts of a ditch possibly dug around the keep and a number of ancillary buildings. It is to be hoped that more excavations will be carried out in the keep itself and in the area near the north tower, where it is evident that the Great Hall of the castle once stood.
Located 28 miles NW of Dublin on the SE side of the old town.
NGR: N 202564.
The keep is presently under conservation, but visitors can gain access to the bailey, either through the west gate (if open) or by walking around the walls to the Boyne front.