Trim Castle on the shores of the Boyne has an area of 30,000 m². It is the remains of the largest Norman castle in Europe, and Ireland's largest castle. It was built primarily by Hugh de Lacy and his son Walter.The central three-story building, called a keep, donjon or great tower, is unique in its design, being of cruciform shape, with twenty corners. It was built in at least three stages, initially by Hugh de Lacy (c.1174) and then in 1196 and 1206 by Walter de Lacy. The keep was built on the site of a large ring work fortification that was burnt down in 1172 and rebuilt in 1173, following attacks by the Gaelic King of Connacht, Ruaidrí Ua Conchobair Rory O'Connor.17th century buildings added to the end of the hall range and to the north side of the keep and a series of lime kilns, one dating from the late 12th century the remainder from the eighteenth and nineteenth centuries.