Big Ben is a clock tower built in a Neo-gothic style. It is almost 100 meters high. The London clock, which is famous all over the world, has 7 meters in diameter and its design was selected in result of the competition the conditions of which were determined by the royal astronomer himself. The clock measures time very precisely – with an accuracy of one second. Due to that fact, the moments when the clock was late because of snowfall or in result of a failure, have been well remembered by Londoners.