King Abdullah, Custodian of the Two Holy Mosques, Friday night officially launched a historic SR40 billion extension project for the Grand Mosque. The project is intended to allow the Haram courtyards complex to accommodate about two million worshippers at a time. The site, where 10,000 workers are already working round-the-clock, covers an area of 400,000 sq. meters. The project envisages a multi-level extension on the north side of the mosque, together with stairways and tunnels to facilitate worshippers access to the Holy Haram. The Grand Mosque underwent significant expansion in the mid-1980s, but the number of Muslim pilgrims has steadily grown, requiring another expansion. King Abdullah also officially inaugurated the 601-meter Makkah Royal Clock Tower, topped with a gigantic four-faced clock that rises from behind the hills and helps visitors at other holy sites locate the Grand Mosque. The clock tower is the world's second tallest building — behind the Burj Khalifa, the 828-meter (2,717-foot) skyscraper inaugurated in Dubai early last year. Makkah, which during the annual Haj pilgrimage attracts some 2.5 million Muslims from around the world for a stay of two weeks on average, last November opened a metro service that will operate only during the Haj season. A proposed SR37.5 billion high-speed train linking Jeddah to Madina via Makkah is also in the cards, with European and Asian companies locked in fierce competition for the project. Muhammad Al-Khozaim, Vice President of the Presidency of the Affairs of the Two Holy Mosques, PTHM, said the new expansion would increase the Grand Mosque's capacity by nearly 1.2 million worshippers. The new project covers 400,000 square meters in the northwest and northeast of the mosque. Real estate properties appropriated for the project are valued at more than SR40 billion. The new expansion was ordered to accommodate the increasing number of pilgrims who come from different parts of the world.