Located at the confluence of the Eresma and Clamores rivers, the first written reference to its existence is Christian and dates back to the beginning of the 12th century. It was built on a rock, which indicates its original military use. It served as a residence for Alfonso VIII. In the 13th century the building acquired a Gothic appearance with the intervention of the architects of Juan II and Enrique IV. The last architectural phase occurred in the year 1587, at the hands of the architect Francisco de Mora, possibly in collaboration with Juan de Herrera, who created the Main Courtyard and the School of Honor. Declared a Historic-Artistic Monument in 1931, in 1985 it was declared a World Heritage Site.