Cordoba is a medium-sized city in the province of Andalusia in southern Spain. It lies on the banks of the Guadalquivir river to the south of the Sierra Morena, about 200km northeast of Seville. Cordoba was conquered by the Romans in 206 BC and later was ruled by the Visigoths and the Byzantine empire. In 711 AD Cordoba was captured by the Arabs, who kept the city for over 500 years. Under Muslim rule Cordoba became the capital of the caliphate of al-Andalus. At its apogee in the 10th and 11th centuries Cordoba was one of the most advanced cities in the world with over 500000 inhabitants. In 1236 AD Cordoba was conquered by the Spanish kings and has been part of Spain ever since. The major attractions of Cordoba are the Mezquita, a mosque converted to a Christian church, and the old town with its narrow alleys and pictoresque buildings. The historic centre of Cordoba has been a UNESCO World Heritage site since 1984.