Big Ben (L) and the Mecca Clock Tower (R) are now in competition to be recognised as the Height of Clock Towers:
St Stephen's Tower: 315.9ft
Royal Mecca Clock Tower (when spire is added): 1,970ft.
Diameter of clock faces:
Big Ben: 23ft
Royal Mecca: 151ft
Big Ben: "Domine Salvam Fac Reginam Nostram Victoriam Primam" (Lord, keep safe our Queen Victoria I)
Royal Mecca: "In the name of Allah"
Big Ben: Originally gas light, now each dial is lit by 28 bulbs.
Royal Mecca: 2 million LED lights on the clock face; 21,000 white and green lights above the timepiece that flash five times a day to signal the call to prayer. 16 bands of vertical lights will also be beamed 7 miles into the air on festival days.
Other claims to fame:
Big Ben: Until now, the great bell was housed in the world's tallest four-faced clock tower. It might still be the world's most recognisable clock, but its significance is dwindling for many ever since the BBC World Service's English services stopped broadcasting the "bongs" on a daily basis (now only happens at 0000 GMT on New Year's Day). Some local language BBC networks still play the chimes of Big Ben.
Royal Mecca: The largest of seven towers making up the Abraj al-Bait complex. It will house a giant shopping mall, over 2,000 hotel rooms, two helipads and a prayer area that can fit 30,000 people. The hotel in the clock tower itself will have 800 rooms. The Palace of Westminster has 1,100 rooms.
The complex is being built by the Bin Laden Group, Saudi Arabia's largest construction company owned by relatives of the terrorist kingpin. Although the clock tower will be hailed as a masterpiece of Islamic architecture, it is in fact being designed by a German company.