Mecca kilometer elevated metro transports pilgrims to holy sites Mount Arafat, Muzdalifah and Mina in the city during hajj reducing the congestion on the roads. Mecca Metro, officially known as Makkah Mass Rail Transit, is a planned four-line metro system for the city. This will be in addition to the Al Mashaaer Al Mugaddassah Metro which carries pilgrims during Hajj. A high speed inter-city rail line (Haramain High Speed Rail Project also known as the "Western Railway"), is under construction in Saudi Arabia. It will link along 444 kilometres (276 mi), the Muslim holy cities of Medina and Mecca via King
Mecca infrastructure, home to structures 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. During this expansion, Mecca has lost some historical structures and archaeological sites, such as the Ajyad Fortress. Today, more than 15 million Muslims visit Mecca annually, including several million during the few days of the Hajj. As a result, Mecca has become one of the most cosmopolitan cities in the Muslim world, although non-Muslims are prohibited from entering the city. "Mecca" is the familiar form