Cairo. Cairo is the capital of Egypt. The city's metropolitan area is one of the largest in Africa, the largest in the Middle East and 15th-largest in the world, and is associated with ancient Egypt, as the famous Giza pyramid complex and the ancient city of Memphis are located in its geographical area. Located near the Nile Delta, modern Cairo was founded in 969 AD by the Fatimid dynasty, but the land composing the present-day city was the site of ancient national capitals whose remnants remain visible in parts of Old Cairo. Cairo has long been a centre of the region's political and cultural life, and is titled the city of a thousand minarets for its preponderance of Islamic architecture. Cairo is considered a World City with aBeta + classification according to GaWC. Cairo has the oldest and largest film and music industries in the Middle East, as well as the world's second-oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city; the Arab League has had its headquarters in Cairo for most of its existence. With a population of over 9 million spread over 3,085 square kilometers, Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live in close proximity to the city. Cairo, like many other megacities, suffers from high levels of pollution and traffic. Cairo's metro, one of two in Africa, ranks among the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy 2010 Global Cities Index. Egyptians often refer to Cairo as Maṣr, the Egyptian Arabic name for Egypt itself, emphasizing the city's importance for the country. The location of the ancient city of Heliopolis is the suburb of Ain Shams. Sometimes the city is informally referred to as Kayro by people from Alexandria. The area around present-day Cairo, especially Memphis that was the old capital of Egypt, had long been a focal point of Ancient Egypt due to its strategic location just upstream from the Nile Delta. However, the origins of the modern city are generally traced back to a series of settlements in the first millennium. Around the turn of the 4th century, as Memphis was continuing to decline in importance, the Romans established a fortress town along the east bank of the Nile. This fortress, known as Babylon, was the nucleus of the Roman and then the Byzantine city and is the oldest structure in the city today. It is also situated at the nucleus of the Coptic Orthodox community, which separated from the Roman and Byzantine churches in the late 4th century. Many of Cairo's oldest Coptic churches, including the Hanging Church, are located along the fortress walls in a section of the city known as Coptic Cairo. Following the Muslim conquest in 640 AD, the conqueror Amr ibn As settled to the north of the Babylon in an area that became known as al-Fustat. Originally a tented camp Fustat became a permanent settlement and the first capital of Islamic Egypt. In 750, following the overthrow of the Umayyad caliphate by the Abbasids, the new rulers created their own settlement to the northeast of Fustat which became their capital. This was known as al-Askar as it was laid out like a military camp. A rebellion in 869 by Ahmad ibn Tulun led to the abandonment of Al Askar and the building of another settlement, which became the seat of government. This was al-Qatta'i, to the north of Fustat and closer to the river. Al Qatta'i was centred around a palace and ceremonial mosque, now known as the Mosque of ibn Tulun. In 905, the Abbasids re-asserted control of the country and their governor returned to Fustat, razing al-Qatta'i to the ground.