Near which European city can visitors explore the ruins of this 10th-century palace-city?

Just west of Córdoba, Spain stands Medina Azahara (also known as Madinat al-Zahra), a fortified palace-city built by Caliph Abd ar-Rahman III (912-961).

Construction on the architectural masterpiece began in 940, and continued throughout his reign and that of his son, Al-Hakam II (r. 961 - 976). The city had ornate reception halls, a mosque, administrative and government offices, aristocratic residences, gardens, a mint, workshops, barracks, service quarters, and baths. Water was supplied through aqueducts. Chroniclers recorded staggering statistics: 10,000 labourers set 6000 stone blocks a day, with outer walls stretching .94 miles (1,518 m) by .46 miles (745 m).

The palace complex spills down a hillside, with the caliph’s palace on the highest levels, overlooking what was likely gardens and fields. The rest of the city (still unexcavated) sat to the sides. Legend has it that Abd ar-Rahman III built Medina Azahara for his favourite wife, Az-Zahra, however it is equally likely that the declaration of his caliphate in 929 was what spurred him to construct himself a new capital.

After al-Hakam II's death, the city was no longer the center of government; the new ruler moved his capital elsewhere in 981. Between 1010 and 1013, it was sacked during a civil war and abandoned, although many of the materials were used elsewhere.

Excavation on the site began in 1911. In 2018, The United Nations Educational, Scientific and Cultural Organization declared it a World Heritage Site.