Llanilid Castle is a very well-preserved raised ringwork which once protected a timber Norman castle. The ringwork measures about 30 metres wide, and has a counterscarped bank to the west. The interior of the enclosure is about 4 metres higher than the exterior, which, though not precisely a motte, does create a more easily defensible position.
History
We are on shaky ground when it comes to the castle's history. Our best guess is that the ringwork was constructed by the powerful St Quintin family, who were lords of the manor until 1245. The original fortification would have been a simple timber palisade. Unlike other castle, the timber structure was never rebuilt in stone, and it seems that when the manor passed to the Siward family they built a completely new moated site nearby and left the original castle site to decay.

The fortification took advantage of a natural hillock sculpted by glaciers, so all the St Quintins needed to do was level the hillock's top and surround it with a ditch and earthen bank. A single causeway crosses the ditch on the south side, directly in line with the medieval parish church.