Abraj Al Bait is a government-owned complex of seven skyscraper hotels in Mecca, Saudi Arabia. These towers are a part of the King Abdulaziz Endowment Project that aims to modernize the city in catering to its pilgrims. The central hotel tower, the Makkah Clock Royal Tower, is the fourth-tallest building and sixth-tallest freestanding structure in the world. The clock tower contains the Clock Tower Museum that occupies the top four floors of the tower.
The building complex is meters away from the world’s largest mosque and Islam’s most sacred site, the Great Mosque of Mecca. The developer and contractor of the complex is the Saudi Binladin Group, the Kingdom’s largest construction company. It is the world’s second most expensive building, with the total cost of construction totaling US$15 billion. The complex was built after the demolition of the Ajyad Fortress, the 18th-century Ottoman citadel on top of a hill overlooking the Grand Mosque. The destruction of the historically significant site in 2002 by the Saudi government sparked an outcry and a strong reaction from Turkey.
The building is topped by a four-faced clock, visible from 25 kilometers away. The clock is the highest in the world at over 400 m above the ground. The clock faces are the largest in the world, surpassing the Cevahir Mall clock in Istanbul. Behind the clock faces, there is an astronomy exhibition. In the spire base and the iron-covered floors (The Jewel) there is a scientific center that is used to sight the moon at the beginning of the Islamic months, and to operate an atomic clock that controls the tower clock faces.
Each of the clock’s four faces measures 43 m in diameter and are illuminated by 2 million LED lights, with four oriented edges, just above the clock alongside huge Arabic script reading: “God is [the] greatest” on the north and south faces and on the west and east “There is no god but Allah. Muhammad is the messenger of God.”. Four golden domes on pillars on all the corners are also present. The same as the Saudi Flag, fitted at the top of the clock, flash to signal Islam’s five-time daily prayers. On special occasions such as new year, 21,000 green and white xenon bulbs and LED lamps during the call to the five prayers times of the day. On special occasions, 40 beacons lights allow innumerable variations of splendid lighting effects. In. addition, the world’s strongest four show lasers throw their rays 30 kilometers into the sky. The clock’s four faces are covered with 98 million pieces of glass mosaics. The Saudi coat of arms is displayed at the center of each clock behind the dials. The minute hand is 23 m long, while the hour hand is 18 m long.
The spire has an eight-story glass-covered base (The Jewel) which belongs to a scientific center having its own small exhibition, another observation deck at 484 m. The highest floor in The Jewel is the Control Tower Floor, which was planned to be used for controlling air traffic in the sky above Mecca (mainly helicopters as airplanes are not allowed near Mecca). However, this was skipped for technical reasons and the future usage is not clear yet. Above from The Jewel the spire has only technical installations for sound, light and other infrastructure and eventually the last viewing deck and the crescent above it. The crescent has two regular floors with living areas and a few service floors and rooms.
According to Wikipedia