Trim Castle, Norman castle in Trim, Ireland

Trim Castle is a ruined Norman castle on the south bank of the River Boyne in Trim, County Meath, Ireland. Its centrepiece is a three-storey cruciform keep with twenty corners, built in stages from about 1174 to 1205. Lower ruined walls with empty window openings and a gaping arch extend to the right, and a square battlemented tower rises at the far right. A low stone wall and a small round-towered fragment stand in front of the keep, above the river and a wooden footbridge.

Hugh de Lacy received Meath from Henry II in 1172 and built a ringwork castle at Trim; it was burned by Ruaidrí Ua Conchobair and rebuilt in 1173. His son Walter continued the work, completing the castle in the 1220s, most likely 1224. In the 15th century the Irish Parliament met here seven times and a mint operated in the castle. The Office of Public Works restored it and reopened it to the public in 2000.

The castle's Irish name, Caisleán Bhaile Átha Troim, refers to the ford of the River Boyne below it. In the 15th century the Irish Parliament met here seven times and a mint operated on the site. The ruins later served as a filming location for Braveheart in 1995 and the television series Mystic Knights of Tir Na Nog.

Visitors can explore the main structures on their own or join guided tours that offer deeper insight into the medieval architecture. There are no special equipment requirements or physical demands, though sturdy footwear makes sense since the grounds are uneven.

The main tower has an unusual shape with many angles that medieval builders chose as a clever solution for defensive strength. This geometric design is uncommon in medieval castles and makes the structure architecturally noteworthy.