This great fortress was erected in the Arab Mérida by the Umayyad emir Abderramán II in 835 AD. This work was commissioned to the architect Abd Allah who was inspired by the Byzantine walls and the Christian kingdoms.
The wall was built using archaeological remains of previous civilizations, however, the Arab emir asked exclusively not to use stones from other Roman monuments, since the governor himself was a lover of Roman architecture and culture.
Within the walls was the residence of the governor and much of the city.

The citadel is a World Heritage Site since 1993 and it is possible to visit the remains along with the rest of the archaeological site of Mérida.