The magnificent ruins of this medieval castle stand on the south bank of the River Boyne. The entrance is through the east Tower, opposite Dublin Gate. The central keep, built between 1220 and 1225, consists of two great halls with sleeping accommodation above. Dublin Gate was protected by two drawbridges and a barbican. The City Gate, facing west, still has the original medieval flagstone floor, a portcullis groove and barrel-vaulted arches.