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:
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.