Built in the 15C, the collegiate church of Covarrubias represents a splendid Gothic edifice and is home to the oldest working organ in Castile (17C). It contains more than 30 medieval tombs, including that of Ferdinand González and his wife Doña Sancha. In the treasury museum, in addition to a lavish collection of sculpture, gold and silverware, ecclesiastical garments and primitive paintings, there is a 15C triptych.