Also known as the Castle of Los Velasco or the Towers of Medina, the Fortress of the Condestables de Castilla is an imposing Gothic fortress-palace, currently fitted out as a culture centre and museum.

It was built by Pedro Fernández de Velasco, royal chamberlain to King Henry II of Castile, who had given him the dominion of the village of Medina de Pomar. Its design is very simple: two robust towers with a square floor plan, topped with battlements and joined together by a central lower body, which was used as the main room.
The exterior looks austere and appears to be a thick fortress thanks to the masonry that was used, its dimensions and the lack of openings (there are just some Gothic loopholes and arch-shaped windows). Inside, however, used to be very luxurious, as we can see by the Mudejar-inspired decorative remains that are preserved.
It currently houses the Las Merindades Historic Museum and various cultural and artistic activities take place here.