San Servando Castle is one of the best Mudejar military architecture works in Spain. It was used at different times to defend the confluence of roads that accessed the bridge and as a military defense fortress of the city, so it was the subject of numerous damage and is currently very restored. It was originally erected in the eleventh century by Alfonso VI, who handed it over to the Templars. It is believed that he veiled the El Cid weapons before his reconciliation with the king. Then it became occupied by the friars of Santiago until the extinction of the order, leaving since then, until it was ordered to rebuild by the well-known archbishop Don Pedro Tenorio in 1386. Raised with masonry and red brick, it has a square plan with crenellated walls, hollow cylindrical towers in three of its corners and cubes on the noon and east facades. The north tower is surrounded by medallions, horseshoe arches and outgoing barbacanas. The doors are clearly Mudejar.