10 things you probably didn't know about Parliament
Veteran documentary maker Michael Cockerell has a new series starting in February, called Inside the Commons.
After asking for access to Parliament for six years, he was eventually granted permission to film in places where cameras have never been allowed before.
I have seen the first of the four programmes, and these are my 10 favourite facts from it, featuring swords, purple ribbons, abseiling rope and what is known as the "plastic fantastic"...
The Palace of Westminster - Parliament - was built on the site of William the Conqueror's first palace.
Rebuilt in Victorian times as a Gothic fantasy palace, it is an eight-acre jumble of buildings, courtyards, passageways and corridors.
There are 100 staircases, more than 1,000 rooms and three miles of passages.
There are purple ribbons attached to the coat-hangers in the members' cloakroom, allowing MPs to hang up their swords as well as their coats. At least one MP still takes advantage of this.
An impressive 300 panes of glass cover the clock-face known to many as Big Ben.
In fact, Big Ben is actually the name of the bell inside the clock-tower.
Once every five years the clock-face is cleaned from the outside, by a team who abseil down it to do their maintenance work. Not a job for anyone scared of heights!
There are 650 MPs elected to the House of Commons. 502 of them are men; 148 are women.
Despite there being 650 MPs, the chamber has only 427 seats - meaning there is often standing room only on big days, such as the Budget.
However, there is a rather arcane way of booking a seat to guarantee a spot on the green benches.
MPs have to roll up at 8am, and place a "prayer card" in the place they would like to sit. They then have to be in the chamber at the start of that day's sitting, for prayers.
For over four centuries, every day in the Commons has begun with prayers, which last for three minutes and require MPs to face the wall for the duration.
There are competing theories as to why this is the custom.
Applause is very, very rare in the House of Commons. Tony Blair received a standing ovation on the day he stood down as prime minister and left chamber for the final time.
There was also an outbreak of applause for Sir Robert Rogers, who retired last year as clerk of the Commons. Sir Robert described the clapping as "really, really moving". But Conservative MP Jacob Rees Mogg said: "I think applause is a bit modern for the House of Commons."
Parliament produces 80 million printed pages a year, ranging from the official parliamentary record - called Hansard - to committee reports and draft legislation.
The thick file of information, carefully labelled to help David Cameron quickly find what he needs at Prime Minister's Questions, is known in Downing Street as the "plastic fantastic".
When a proposed new law, a bill, is sent from the House of Commons to the House of Lords, the clerk of the Commons writes "Soit bail as Seigneurs" on it - which means "let it be sent to the House of Lords" - in Norman French...
...the bill is then tied up in green ribbon, the colour of the House of Commons, and carried by hand through Central Lobby into the House of Lords.
The first episode of Inside the Commons, an Atlantic Productions for BBC Two, is broadcast on Tuesday on BBC Two at 21:00 GMT.