Enniskillen Castle, situated beside the River Erne in County Fermanagh, was built almost 600 years ago by Gaelic Maguire chieftains. The chieftain at the time, King Thomas Maguire, (Thomas the Great) ruled from Lisnaskea in the south-eastern part of the county. His younger brother, Hugh 'The Hospitable' Maguire, was deputy chieftain and he is credited with building Enniskillen Castle, locating it in a strong defensive position beside the River Erne.
The Keep incorporates the remains of the original medieval castle of the Maguires. The original castle, a small square tower-house, guarded one of the few passes into Ulster and defended Fermanagh from attack. In the 17th century the site became an English garrison fort and later served as part of a military barracks. The two-storey block which curves around the western perimeter of the site, was built to accommodate the soldiers, horses and gun carriages of the resident cavalry regiment - the Inniskilling Dragoon Guards.
The Watergate is a twin-turreted structure, built by William Cole in the early 17th century and has become an iconic symbol of Enniskillen and of County Fermanagh. Scottish in style and designed to impress, it was part of the outer defences of the castle.
Enniskillen Castle represents an important part of Fermanagh's rich history and heritage. This historic site houses two museums, Fermanagh County Museum and The Inniskillings Museum.