On the highest hill in the city, with 548 m, the lonely rectangular mole of the Alcazar dominates the horizon. It is one of the few exempt buildings in the city. The vestiges of the previous structures indicate that it was always a fortified place, from the Roman praetorium and the defense of the Muslim citadel.

The current building was ordered to be built by Emperor Carlos V, to have a residence worthy of such a monarch. For this, the previous medieval castle was almost completely destroyed, although there are crenellated structures on the eastern facade. Each facade of the building artistically determines the moment in which it takes place, within the various phases of the Spanish Renaissance.

For years it housed part of the catalog of the Army Museum, being adapted to house it in its entirety, as the only national site of this collection and inaugurated as such in 2010. Works were also carried out enabling the upper floor of the building to the needs of the Modern Library of Castilla-La Mancha.