Alcazaba of Mérida
Located near the Roman bridge over the Guadiana river, the Puente Romano, it was built by emir Abd ar-Rahman II of Córdoba in 835 to command the city, which had rebelled in 805. It was the first Muslim alcazaba, and includes a big squared line of walls, every side measuring 130 metres in length, 10 m of height and 2.7 m thickness, built re-using Roman walls and Roman-Visigothic edifices in granite. The walls include 25 towers with quadrangular base, which also served as counterforts. Inside is an aljibe, a rainwater tank including a cistern to collect and filter water from the river.
The Alcazaba is accessed from the Puente Romano through a small enclosure, traditionally known Alcarazejo. This was used to check the traffic of pedestrians and goods to the city. Annexed is the military area, whose gate is flanked by two towers; over the horseshoe-shaped arc is an inscription celebrating Abd ar-Rahman patronage of the work.