Cordoba, Spain

At its peak in the 10th century, Cordoba was one of the largest and most advanced cities in the world, with estimates of its population reaching up to 500,000 to 1 million inhabitants, dwarfing contemporary European capitals like Paris or London.

During the Islamic Caliphate, Cordoba boasted over 700 mosques, 300 public baths, and an estimated 70 libraries, including the Caliph's library which alone held possibly hundreds of thousands of manuscripts, making it a pivotal center of learning in medieval Europe.

Cordoba's unique 'Festival de los Patios' (Courtyard Festival), where residents open their elaborately decorated private patios to the public, was declared a UNESCO Intangible Cultural Heritage of Humanity in 2012.

Cordoba holds the distinction of being the only city in the world with four UNESCO World Heritage Sites: the Mezquita-Cathedral, the Historic Centre (which encompasses much of the old town), the Festival of the Patios, and the archaeological site of Medina Azahara.

Beyond the famous Patios Festival, Cordoba also hosts an annual 'Concurso de Rejas y Balcones' (Grilles and Balconies Competition), where residents adorn their street-facing ironwork with an explosion of flowers, turning the city into a vibrant floral tapestry throughout May.

The Mezquita-Cathedral is a singular architectural wonder, featuring over 850 double-tiered arches supported by columns of jasper, onyx, marble, and granite, creating a 'forest' effect. It seamlessly blends Islamic and Renaissance Christian architecture following its conversion after the Reconquista.

During its Golden Age, Cordoba was a melting pot of Christian, Jewish, and Muslim scholars. Its intellectual output, particularly in philosophy (e.g., Averroes and Maimonides), medicine, mathematics, and astronomy, profoundly influenced the European Renaissance and the transmission of knowledge from the East.

A curious legend tells of a giant crocodile, or 'Cocodrilo del Guadalquivir,' that supposedly terrorized the river until it was hunted down in the 17th century. Its stuffed remains (actually a large loggerhead turtle shell) were once displayed in the Calahorra Tower as a cautionary tale.