1840-2012: Big Ben and Elizabeth Tower

Construction of the new Palace of Westminster began. Architect, Charles Barry won the commission to design the new palace and included a clock tower in his final designs

Construction began on the Clock Tower 

A competition was held to decide who should build the clock. The Astronomer Royal, Sir George Airy was the referee. Stipulations for the clocks accuracy meant it took seven years before the designs were finalised

John Dent was appointed to build the clock to the designs of Edmund Beckett Denison. This was the same year that the new Palace of Westminster, designed by architect Sir Charles Barry with the assistance of Augustus Welby Pugin, was opened by Queen Victoria at the State Opening.

The clock was completed

The first 'Big Ben' bell was cast at Warners of Norton near Stockton-on-Tees, the bell was originally to be called 'Royal Victoria'

The first 'Big Ben' developed a four inch crack during testing and was condemned and Warners, the bell's manufacturer, and Edmund Beckett Denison, designer of the Great Clock, clashed over who was responsible.

The second 'Big Ben' was cast by the Whitechapel Bell Foundry in east London. It was transported to New Palace Yard on a carriage drawn by 16 white horses and raised to the belfry.

The Great Clock first started keeping time in May and in July Big Ben first struck time with the Great Clock. Later in the year, Big Ben was found to be fractured in two places. While a solution was sought, the largest quarter bell struck the hour

At the suggestion of Sir George Airy, the Astronomer Royal, Big Ben was turned by an eighth and the hammer size was reduced thus allowing Big Ben to strike the hours once more

BBC Radio first broadcast Big Ben's chimes to the United Kingdom on New Year's Eve

Big Ben's strikes broadcast internationally for the first time by the Empire Service (later the World Service) as part of King George V's Christmas broadcast.

From this date until April 1945, the clock dials were unlit to comply with blackout regulations during the Second World War

The 'Silent Minute' was introduced. Each night, before the 9pm BBC radio news, people were encouraged to remember those away fighting in the Second World War, for the minute it took to broadcast Big Ben's chimes

The clock dials were re-illuminated when the wartime blackout regulations were lifted

In the middle of the night on the 10 August, a mechanical failure caused serious damage to the Great Clock. The pendulum weights fell out of control down the shaft and the clock mechanism exploded. Big Ben was silenced for nearly nine months while repairs were carried out.

Big Ben and the quarter bells were silenced while the Great Clock underwent essential maintenance work for seven weeks

Big Ben celebrated its 150th anniversary with a year of events and activities

The Clock Tower was renamed the Elizabeth Tower to honour Queen Elizabeth's Diamond Jubilee