Mecca Clock Tower: largest, tallest and the biggest - 18 Pics+Video

Saudi Arabia will test what it is billing as the world's largest clock in the holy city of Mecca during the Muslim fasting month of Ramadan.

The four-faced clock tower will top a massive skyscraper that when completed will be around 1,970 feet (600 metres) tall, the second tallest in the world after Dubai's Burj Khalifa.

The clock will dwarf London's Big Ben, once the largest four-faced clock in the world, with dials more than five times greater in area.

The around 130 foot (40 metre) diameter Saudi clock dials are also bigger than the current world champion at the Cevahir Mall clock in Istanbul, which has a 36 metre face set in the transparent roof of the shopping complex.