Ordered to be built in 1440 by Don Alonso Pérez de Vivero, Viscount of Altamira and accountant of Juan II, this castle-palace, originally featuring towered corners, was the site of the marriage, on 19 October 1469, between Doña Isabel de Castilla and Don Fernando de Aragón. When the Royal Court Chambers and Chancellery were later moved, the Catholic Kings gave the structure a new use, transforming the palace rooms into chambers for royal audiences. Of interest is its Mudejar coffering in the principal chamber. Presently it houses the Archive of Provincial History.