The ruins of Oystermouth Castle stand on a hill above Mumbles village, with views over Swansea Bay. The castle was begun in the early twelfth century as the seat of the Norman lords of Gower and remained in use through the medieval period.
A 2011 restoration added a glass bridge across the inner ward and an open-air theatre that hosts summer plays. The walk up from the village takes about ten minutes, and the gardens around the ruins are a nice spot for a picnic. Open daily in the warmer months; check times in winter.