Also known as the Houses of Parliament where MPs sit in the House of Commons and Lords sit in the House of Lords, the palace was built by the River Thames in 1016.
It was then demolished by a fire in 1834 and had to be rebuilt in 1840, that's 176 years ago and now there's a really long list of repairs that need to be done to the historic building to stop it from falling into the River Thames.
The idea is that MPs and Lords move out of the Houses of Parliament while the work is carried out, work that is estimated to cost US$4.9 billion.
However, SNP MP Neil Grey, a member of the joint committee for the Palace of Westminster, says it could cost a lot more than that.
"My hunch is it will be significantly more than that once the full details of the project are gone through and once we get into the bones of delivering it."
Should we vote on the £4bn Houses of #Parliament refurbishment? https://t.co/9nzWA8kYCC @BuildSpecifier #refurb #government #construction
— UK Recruiting Ltd (@UKRECltd) September 8, 2016
"Any DIY job on an old building always throws up problems. I suspect with a building like the Palace of Westminster, where you've had add-ons, removals and old-fashioned antique construction, you're going to find some pretty expensive pitfalls along the way."
Neil Grey told The House magazine that he could "almost guarantee the costs are going to be higher than £4 billion," and suggested that MPs consider leaving the Palace of Westminster permanently.
"My concern the whole way through the process on the committee was 'are we artificially crow-barring a parliament into an old palace at a premium?' I think that is borne out in the costs that we're looking at," he said.
So What Needs Doing?
Asbestos: basically needs removing from any post-war restoration work carried out in the building. Exposure to asbestos can be fatal.
Leaking pipes: the pipework in the palace is around 130-years-old as has never been replaced — or when it was, it was treated with asbestos.
Leaking roofs: installed in the mid-1880s, they're leaking and practically falling apart and desperately needs fixing as any leaks could damage the historic interior.
Why didn't @George_Osborne take his own advice & fix the roof while the sun is shining? We are still running £100bn deficit.
— NOT Diane Abbott MP (@hackneyabbatt) June 15, 2016
Windows: and there's not just a few — there's 4,000 of them and most of them don't open or close and they're not exactly double-glazed.
Rats, and lots of them apparently.
The Hermitage Museum in St Petersburg has 30 working cats to keep the rats and mice down. Houses of Parliament need to follow suit.
— Mary Archer (@MaryDArcher) July 29, 2015
Decaying stonework: the limestone used in the palace at the time was both cheap and good for carving, but now it's decaying and in need of restoration and cleaning.
£4bn to fix the Houses of Parliament? I'm sure Guy Fawkes was quoting less.
— Neal Spinks (@nealspinks) September 8, 2016
With the list of refurbishments growing — it's not really surprising the bill to fix them is too.