Carrickfergus Castle, a Norman-built castle, and one of the best-preserved medieval structures in Ireland, has seen over 800 years of military occupation. The castle was besieged in turn by the Scots, Irish, English, and French and it continued to play a central part in a military role until 1928, today it is maintained by the Northern Ireland Environment Agency. Surrounded by sea, the keep of the castle is a four-story tower, 90 ft high, with a second-story entrance. Its entry chamber, originally one large, poorly lit room with a double latrine and no fireplace, served as the public room. A shaft gave access to a well below and a mural stair led down to the vaulted storage cellar. The fourth story, a high, brightly lit room with windows in all four walls, a fireplace and single latrine, was the principal chamber. Visitors to the castle can avail of a self-guided tour of the walls or, on occasion, guided tours can be arranged by the Carrickfergus Historical Society. Also open to the public for fun days out, the impressive monument has canons from the 17th and 19th centuries on display, while the keep houses historical and other displays.