An inscription on the palace's foundation stone, today located in the city's archaeological museum, explains that the Alcazaba of Merida was constructed on an earlier Roman site in the year 835 by the governor 'Abd Allah ibn Kulaib, for the Emir, 'Abd ar-Rahman ibn al-Hakam. This stronghold overlooks the Guadiana River and the adjacent Roman bridge. It contributed to safeguarding the region as it was one in a series of fortresses constructed along the Christian border with Islamic southern Spain.
Built using Roman and Visigothic masonry, the fortification measures approximately 130 square meters and is buttressed by four rectangular corner bastions with towers scattered between them on each side, usually symmetrically. The main entrance, featuring horseshoe arches, opens on the north side and proceeds into a small courtyard that leads both into the city and the inner citadel. Once castellated, the walls extend 2.7 meters thick and introduce the earliest example in Spain of an albarrani, a tower that extends from the palace to connect with a bridge. Dating to the same period as the walls, a large cistern, or aljibe, provided a direct source of water from the river into the fortress by means of a vaulted stone corridor with Visigothic pilasters. Two staircases lead deep into the cistern's pool for retrieving water. Overall, the Alcazaba is reminiscent of Syrian building technique.
While it had been bequeathed to the Order of Santiago under succeeding Christian rule, this fortress today serves as a museum.
Creswell, K. A. C.1989. A Short Account of Early Muslim Architecture. Rev. ed. Allan, James W. Aldershot: Scolar Press, 302-303.