Cordoba is a city in Andalusia, southern Spain, and the capital of the province of Cordoba. It was conquered by Muslim armies in the eighth century, and then became the capital of the Islamic Emirate and then Caliphate of Cordoba, including most of the Iberian Peninsula. Caliph Al Hakam II opened many libraries in addition to the many medical schools and universities which existed at the time, making Cordoba a centre for education. During these centuries, Cordoba became a predominantly Muslim society with minorities living in peace and harmony with their Muslim neighbours. It returned to Christian rule in 1236, during the Reconquista. Today it is a moderately sized modern city; its population in 2011 was about 330,000. The historic centre was named a UNESCO World Heritage Site. Cordoba has the warmest summer high temperatures in Spain and Europe with average high temperatures around 37°C in July and similar heat in August.