There may have been earlier castles at this site, but the Mombeltran castle we see today was built by Don Beltrán de la Cueva, the first Duke of Alburquerque. He placed his coat of arms and those of his successive spouses above the entrance gate. This makes us believe that the construction of the castle took place between 1462 and 1474. The castle was donated to Don Beltrán by King Enrique IV, in 1461. Because there's architectural similarity between this castle and Belmonte Castle and Manzanares el Real Castle its architect probably has been Juan Guas. Although Mombeltrán Castle has a military and defensive appearance there are also many details of luxury for a palatial residence. Also in the 16th century the castle was modified for even more comfort.
Basically the castle is a square of rubblework and granite ashlar masonry with circular towers in the corners. The largest of those towers was the keep which has a central column in its interior on which the floors rest. Around the castle there is a second enclosure which closely follows the outlines of the inner one. This enclosure is equipped with a barbican.
Mombeltrán Castle lies on a beautiful spot, in the mountains of the Sierra de Gredos.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.