Fes or Fez is the second largest city of Morocco, after Casablanca and Rabat, with a population of approximately 1 million (2010). It is the capital of the Fes-Boulemane region. Fes, the former capital, is one of the country's four "imperial cities," the others being Rabat, Marrakech and Meknes. It comprises three distinct parts, Fes El Bali, Fes-Jdid and the Ville Nouvelle. Fes el Bali is a UNESCO World Heritage Site. Its medina, the larger of the two medinas of Fes, is believed to be the world's largest contiguous car-free urban area. The University of Al-Karaouine, founded in AD 859, is the oldest continuously functioning university in the world. The city has been called the "Mecca of the West" and the "Athens of Africa". The city was founded on a bank of the Fez River by Idris I in 789, founder of the Zaydi Shi'ite Idrisid dynasty.