This typically Galician noble fortress with medieval origins has been splendidly conserved and restored and today functions as a library, cultural centre and exhibition venue.

The castle originally belonged to the House of the Counts of Lemos, and became part of the House of Alba in the 18th century. It was built in the 14th century as a fortress with a purely military function, and was renovated in the 16th century and converted into a palatial residence.
Its floor plan is in the shape of an irregular polygon, as it adapts to the hill on which it stands. It comprises several parts or buildings, of which the rectangular keep and the clock tower are the oldest. Other surviving elements include the bailey, sections of the defensive wall –with numerous carved crests, in addition to battlements, barbicans and arrow slits–, three square towers, the administrator's house, the palace –containing the library, a museum about the castle and other rooms–, the interior sentry walk and the outer moat.