Big Ben was originally the name of the bell that sits inside the 315-foot Elizabeth Tower, and it turned 160 years old on Thursday.
Although it first rang the hour on July 11, 1859, Big Ben has been silent since the Elizabeth Tower restoration project started in 2017, according to a press release from Parliament.
Work is now at its halfway point, and the most extensive conservation program ever carried out on the tower is expected to finish in 2021.
While Big Ben has remained in place throughout the project, components from the clock's 11-ton mechanism have been winched down to the ground to protect them from damage.
Every cog and wheel has been serviced by clock makers; a North Dial has been re-glazed, repainted and re-gilded; and 324 individual pieces of glass are being installed into the dial frame by stained-glass artists.
"It is a testament to the craftsmanship that went into its creation, and the expert team maintaining it, that 160 years since Big Ben rang out on 11 July 1859, both the Great Bell and the Great Clock still remain in fantastic condition," said Steve Jaggs, keeper of the Great Clock.
The 3,433-piece cast iron roof is now being reinstalled after it was removed and restored, and the carved stonework -- which includes angels, lettering and symbolic creatures -- has been "meticulously cleaned."
"This is a complex program, with hundreds of experts around the country working on different elements of the project," said Charlotte Claughton, senior project leader, in a statement.
Claughton said the hard work of those involved meant the project was progressing well.
"It means that late next year we will be in a position to start taking down scaffolding to reveal this much-loved landmark restored to its former glory," she added.
Once the Elizabeth Tower reopens, it is hoped that there will be more capacity for visitors to tour the tower.
However, as of now, there are no detailed forecasts on how many people will be able to visit the restored tower, according to a statement from the House of Commons.