The Alcazaba of Mérida stands as a testament to the rich Islamic history of Spain. Constructed in the 9th century by Emir Abd ar-Rahman II, this formidable fortification was built to establish control over the city following a rebellion. Its robust squared walls, towering at 10 meters high and stretching 130 meters on each side, are a marvel of medieval military architecture. Within its confines lies an aljibe, an ingenious rainwater tank designed to collect and filter water from the Guadiana river, showcasing the advanced engineering skills of the era. As part of the Archaeological Ensemble of Mérida, the Alcazaba's inclusion in the UNESCO Heritage List underscores its cultural and historical significance, preserving a legacy that spans over a millennium.