The world's biggest clock tower that cost £11bn and makes Big Ben look tiny

Think of iconic clock towers and the image that likely pops into mind is that of Big Ben in Westminster. Yet there is a more expensive, taller clock tower which cost billions to build and shattered records when it opened.

The Mecca Clock Royal Tower in is the fourth-tallest building and sixth-tallest freestanding structure , as well as the tallest clock tower. It stands at the heart of The Clock Towers, a building complex owned by the government of Saudi Arabia that comprises seven skyscraper hotels in Mecca. The complex is an initiative by the government to improve the pilgrim experience to the holy city of Mecca, a central location in the Muslim faith. It lies 300 metres from the world's largest mosque and the most sacred site in Islam, the Great Mosque of Mecca, which millions of pilgrims journey to each year.

Construction began in 2002 and necessitated the demolition of the Ajyad Fortress, an 18th-century Ottoman citadel which sat on a hill overlooking the Great Mosque.

Its destruction by the Saudi government provoked a strong outcry, particularly from Turkey.

It had stood since 1780, and its dismantling caused some to suggest a boycott on travel to Saudi Arabia, though this did not materialise.

The fortress is now represented in a 1:25 scale model which can be viewed at the Miniaturk miniature park in Istanbul.

In its place, the £11.3 billion complex was built and opened in 2012, with the clock tower itself becoming the tallest building in Saudi Arabia at a height of 601 metres. By comparison, Big Ben stands at just 96 metres.

It also houses a five-star hotel and a five-storey shopping mall, with a car park capable of holding over 1,000 vehicles.

The clock itself features a face on each of the four sides of the main hotel tower, measuring 57 metres in height.

At 43 metres x 43 metres, these clock faces are also the largest of their kind in the world, and there is an astronomy exhibition behind them in the tower.

There is also a scientific centre which observes the moon at the beginning of the months in the Islamic calendar, while it also operatures an atomic clock off of which the clock faces run.

Above the clock, there is an eight-storey covered base called The Jewel, in which the scientific centre is located.

Above this is the final viewing deck and the crescent symbol of Islam, which was constructed in Dubai and weighs 35 tonnes.