Trim Castle through the Yellow Steeple window. Trim, Co Meath, Ireland. Trim Castle, the largest Anglo-Norman castle in Ireland, was constructed over a thirty-year period. Construction of the massive three storied Keep, the central stronghold of the castle, was begun c. 1176 on the site of an earlier wooden fortress. The Yellow Steeple, dating from 1368, takes its name from the golden colour of the stonework at sunset. It is a 40m tall tower that was part of an Augustinian Abbey.