Photo ©Paul R. Davis

The 18 feet high circular motte is situated on the south-western bank of the Afon Aber. It measures 120ft in diameter at the base and 55 feet in diameter at the top and there are traces of a large bailey to the east. It is thought to have been started by Norman lords on the late 11th century, but then became a princely court, one of the principal residences of the princes of Gwynedd through the thirteenth century.