[custom_adv] Mecca is a city in the Hejazi region of Saudi Arabia. 70 km (43 mi) inland from Jeddah, in a narrow valley 277 m (909 ft) above sea level, 340 kilometres (210 mi) south of Medina, its population in 2012 was 2 million, although visitors more than triple this number every year. [custom_adv] Mecca was long ruled by Muhammad's descendants, the sharifs, acting either as independent rulers or as vassals to larger polities. [custom_adv] It was conquered by Ibn Saud in 1925, since then Mecca has seen a tremendous expansion in size and infrastructure, such as the Abraj Al Bait, also known as the Makkah Royal Clock Tower Hotel, the world's fourth tallest building and the building with the third largest amount of floor area. [custom_adv] It is the birthplace of Muhammad, a cave 3 km (2 mi) from Mecca was the site of Muhammad's first revelation of the Quran, and a pilgrimage to it, known as the Hajj, is obligatory for all able Muslims. [custom_adv] Mecca is home to the Kaaba, one of Islam's holiest sites and the direction of Muslim prayer, and thus Mecca is regarded as the holiest city in Islam. [custom_adv] Mecca is a city in the Hejazi region of Saudi Arabia. 70 km (43 mi) inland from Jeddah, in a narrow valley 277 m (909 ft) above sea level, 340 kilometres (210 mi) south of Medina, its population in 2012 was 2 million, although visitors more than triple this number every year. [custom_adv] Mecca was long ruled by Muhammad's descendants, the sharifs, acting either as independent rulers or as vassals to larger polities. [custom_adv] Mecca is home to the Kaaba, one of Islam's holiest sites and the direction of Muslim prayer, and thus Mecca is regarded as the holiest city in Islam. [custom_adv] The Kaaba is a building at the center of Islam's most important mosque, Great Mosque of Mecca, in the Hejazi city of Mecca, Saudi Arabia.