Big Ben and Parliament, Palace of Westminster, London, England

London o'clock. Palace of Westminster, London, England

London's most famous clock tower isn't called Big Ben—that name belongs to the massive 13.5-tonne bell inside. It has marked time for Londoners since 1859, ringing from what is now known as the Elizabeth Tower. In 2012, officials renamed the Clock Tower as Elizabeth Tower to honour Queen Elizabeth II during her Diamond Jubilee. The clock has stopped only for maintenance and rare disruptions, such as bomb damage during World Wars I and II. Each of its four clock faces spans 6.9 metres, with the minute hands measuring 4.3 metres. At 96 metres tall, the tower is part of the grand Palace of Westminster, home to the UK Parliament.

For centuries, the Palace of Westminster has stood at the heart of British politics. Originally built by Edward the Confessor in the 11th century, the palace has hosted Parliament since the 13th century. Previously a royal residence, it remained one until a fire in 1512 forced Henry VIII to relocate. A second devastating fire in 1834 destroyed most of the medieval complex, leading to the Gothic Revival design seen today. Architect Charles Barry led the reconstruction, while his assistant, Augustus Pugin, designed the intricate details. Covering 112,476 square metres, the palace houses the House of Commons, the House of Lords and Westminster Hall, which dates to 1097.