This New Year's Eve, Big Ben will bong with all faces of the Houses of Parliament's famous clock tower on display for the first time since 2017.
The bell will be struck 12 times to mark the start of 2022, as a project to restore the Palace of Westminster's Elizabeth Tower nears its end.
The five-year endeavour in refurbishing the London landmark spiralled to at least £80 million.
In the days running up to December 31 the bell will be heard chiming, as engineers test it ahead of the celebrations.
However only the East Dial, which faces the River Thames, will be illuminated to bring the new year in.
Ian Westworth, one of Parliament's team of clock mechanics who will be making sure Big Ben strikes on New Year's Eve, said: 'It's iconic - it's probably the world's most famous clock, and to have had our hands on every single nut and bolt is a huge privilege.
'It's going to be quite emotional when it's all over - there will be sadness that the project has finished, but happiness that we have got it back and everything's up and running again.'
The chimes on December 31 will also be the final occasion that Big Ben will be struck using a temporary mechanism.
From spring, Big Ben and the four quarter bells will once again sound out the famous Westminster Quarters melody and resonant bongs throughout the day - the first time they have done so since the restoration began in 2017.
Over the past four years, the Elizabeth Tower and the clockwork and bell mechanism within it have undergone the biggest repair and conservation project in its 160-year history.
The tower exterior has been covered in scaffolding for most of the works and the bell was rarely rung in the past four years.
As the scaffolding has been removed in recent months, a view of the clock face's restored original paint colour has emerged.
When black paint was stripped away from the dials during repair work earlier this year, it was discovered that it was originally painted in a dark blue hue known as Prussian blue.
Teams across the UK - including the Cumbria Clock Company - were involved in reviving the much-adored timepiece and bringing back its signature 'bong', which first rang out around London in 1923.
The task has been particularly painstaking given that neither the original designer, Edmund Beckett Denison, nor installer, Edward John Dent, kept detailed records of how it was constructed.
The clock was designed and installed in 1859, with the aim of creating the most accurate public timepiece in the world.
After the Palace of Westminster was destroyed by a fire in 1834 those in charge of planning the new building decided to create a tower and clock.
The bell necessary for the giant clock had to be large, and John Warner and Sons at Stockton-on-Tees' first attempt cracked irreparably.
in 1858 the metal was melted down and the bell recast in Whitechapel.
It first rang across Westminster on May 31, 1859 but just months later cracked again.
A lighter hammer had to be fitted and the bell was turned around so an undamaged section could be rung.
The origin of the name Big Ben is not known, although two different theories exist.
The first is that is was named after Sir Benjamin Hall, the first commissioner of works, a large man who was known affectionately in the house as 'Big Ben'.
The second theory is that it was named after a heavyweight boxing champion at that time, Benjamin Caunt.
Also known as 'Big Ben', this nickname was commonly bestowed in society to anything that was the heaviest in its class.
Big Ben's timekeeping is strictly regulated by a stack of coins placed on the huge pendulum.
Before 2009, timekeepers kept 10 old pennies beside the mechanism, using the coins to keep the clock accurate. It now also used special £5 coins created especially for the 2012 Olympics.
Adding or taking away coins affects the pendulum's centre of mass and the rate at which it swings, Mike McCann, the clock's keeper told Reuters news service at the time.
The clock has rarely stopped - even after a bomb destroyed the Commons chamber during the Second World War, the clock tower survived and Big Ben continued to strike the hours.
The chimes of Big Ben were first broadcast by the BBC on December 31 1923, a tradition that continues to this day.
The latin words under the clock face read Domine Salvam Fac Reginam Nostram Victoriam Primam, which means 'O Lord, keep safe our Queen Victoria the First'.
Source: visitlondon.com