11th – 19th centuries. Built on the remains of a Roman fortress. It was consecutively transformed all the way from king Alfonso VI (11th century) through to king Philip II (16th century). House of the monarchs of Castile during the Middle Ages. The “Old Palace” was amplified in the 15th century with some magnificent rooms: the Throne Hall (Solio), the Galley Hall (Galera), the Pineapples Hall (Piñas), the Monarchs Hall (Reyes), the Cord Hall (Cordón) and the Chapel. The great tower with battlements is called the Juan II Tower, for it was this king who gave it its current aspect. Under the kingdom of Philip II the parade ground and the slate roof slopes were incorporated. The building was a state prison during the 17th and 18th centuries. The king Charles III founded the Royal College of Artillery here in 1764.  Luis Daoíz and Pedro Velarde were two outstanding artillery officers. They became heroes in the war against the Napoleonic invasion of Spain. There is a sculptural group erected in their memory in the centre of the Reina Victoria Eugenia Gardens. The sculptor was Aniceto Marinas. In 1862 the fortress underwent a horrific fire. 

Reconstruction works took place from 1882 to 1896, under the charge of the architect Antonio Bermejo y Arteaga was. Visits to the halls in the palace and to the rooms portraying the history of the Royal College of Artillery are available, as well as access to the terrace, the old “Moors Gallery” (Galería de Moros) and to the tower, which enjoys spectacular views. The building is also the seat of the General Military Archive of Spain.