1.The world's first traffic light was erected outside the House of Commons in 1868. It blew up the following year, injuring the policeman who was operating it.
2.The tomb of Elizabethan poet Edmund Spenser in Westminster Abbey is said to contain unpublished works by his contemporaries - including Shakespeare - who threw manuscripts into his grave to honour his genius.
3. Cars are requiredby law to travel on the right-hand side of the road in Savoy Court - this was originally decreed by Parliament in 1902 so that theatregoers could decamp from their carriages directly into the Savoy Theatre.
4.One, London, is the postal address of Apsley House, the Duke of Wellington's former residence on Hyde Park Corner.
5.Arsenal is the only football club to have its own, eponymous Tube station, even though London's arsenal was based in Woolwich.
6.St Thomas' Hospital used to have seven buildings, one for each day of the week, supposedly so that staff knew on which day patients had been admitted. Only two of the buildings remain.
7. Signs on Albert Bridge order troops to break step while marching over it, to avoid damaging the structure with resonating vibrations.
8.Before the 17ft statue of Nelson was erected on top of the Trafalgar Square column in 1842, 14 members of the memorial committee who had commissioned the work held a dinner party on the 170ft-high plinth.
9. The exact centre of London is marked by a plaque in the Church of St Martin's-in-the-Fields overlooking Trafalgar Square.
10. Brixton Market was the first electrified market in the country and stands, as a result, on Electric Avenue.
11. Dr Samuel Johnson once owned 17 properties in London, only one of which survives - Dr Johnson's Memorial House in Gough Square, which contains a brick from the Great Wall of China, donated to the museum in 1822.
12. The Fleet River - one of the capital's many buried waterways - still runs under the cellars of the Cheshire Cheese pub on Fleet Street.
13. East London is the most popular film location in the city, playing host to everything from Oliver! to A Clockwork Orange and Full Metal Jacket. The naval buildings of Greenwich stood in for Washington in Patriot Games.
14. The Monument to the Great Fire of London was also intended to be used as a fixed telescope to study the motion of a single star by Robert Hooke, who designed the structure with Sir Christopher Wren.
15. Only six people died in the Great Fire of London, but seven people died by falling or jumping from the Monument to it before a safety rail was built.
16. Postman's Park, behind Bart's hospital, is one of London's great hidden contemplative spots. It is full of memorials to "ordinary people" who committed heroic acts.
17.The tiered design of St Bride's Church in Fleet Street is believed to have been the inspiration for the tiered wedding cake.
18. The nursery rhyme Pop Goes the Weasel refers to the act of pawning one's suit after spending all one's cash in the pubs of Clerkenwell.
19. The circular church of Nôtre Dame de Paris in Leicester Place off Leicester Square has a crucifixion mural, including a selfportrait, painted by the French artist Jean Cocteau in 1960.
20. The Piccadilly Circus statue known as Eros, is actually intended to depict the Angel of Christian Charity, and is part of a memorial to the Seventh Earl of Shaftesbury. Its stance, aiming an arrow up Shaftesbury Avenue, is thought to be a coarse visual pun.
21.Pubs in Smithfield, such as the Fox and Anchor, and in Borough, such as the Market Porter, are licensed to serve alcohol with breakfast from 7am to fit in with the hours worked by market porters.
22. The only true home shared by all four Beatles was a flat at 57 Green Street near Hyde Park, where they lived in the autumn of 1963.
23. The gravestone of the famous Elizabethan actor Richard Burbage in the graveyard of St Leonard's, Shoreditch, reads simply "Exit Burbage". The church's burial register also records the death in 1588 of Thomas Cam, aged
24. London was the first city to reach a population of more than one million, in 1811. It remained the largest city in the world until it was overtaken by Tokyo in 1957.
25.The first performance of a Punch and Judy show at Covent Garden was recorded in Samuel Pepys's diary entry for 9 May 1662, and it is believed a similar puppet show has been seen there every year since.
26. The only London theatre not to close during the war was the Windmill in Soho, which then offered a variety show mixing comedy acts with semi-nude female tableaux. It is now a table-dancing club.
27. The Dome, the focus of the Millennium celebrations, is the largest structure of its kind in the world - big enough to house the Great Pyramid of Giza or the Statue of Liberty.
28. Elephant and Castle derives its name from a craftsmen's guild, whose sign featured an elephant in reference to the ivory handles of the knives they made.
29. Pearly Kings and Queens, so called because they wear clothes studded with countless pearl buttons, were originally the "aristocracy" of the costermongers or barrowboys and were elected to safeguard their rights from competitors and rogues.
30. Mayfair is named after a fair that used to be held in the area every May; Piccadilly after a kind of stiff collar made by a tailor who lived in the area in the 17th century; and Covent Garden was originally the market garden for the convent of Westminster Abbey.
31. In 1926, John Logie Baird demonstrated how television would work in what is now Bar Italia in Frith Street, Soho.
32. London's smallest house is three-and-ahalf-feet wide, and forms part of the Tyburn Convent in Hyde Park Place, where 20 nuns live.
33. The Houses of Parliament has 1,000 rooms, 100 staircases, 11 courtyards, eight bars and six restaurants - none of them open to the public. The Palace of Westminster was sited by the river so it could not be totally surrounded by a mob.
34. The site of Tyburn Tree, London's infamous public gallows - where an estimated 50,000 people were hanged - is now a traffic island at the junction of Marble Arch and Edgware Road.
35.The architect of the Oxo Tower, forbidden from including an electrified advertising hoarding in the building, instead incorporated the company's name in the windows on all four sides.
36. It is illegal in London to have sex on a parked motorcycle, beat a carpet in a public park, or impersonate a Chelsea pensioner - the latter offence is still theoretically punishable by death.
37. Marble Arch was designed by John Nash in 1828 as the entrance to Buckingham Palace, but was moved to Hyde Park when Queen Victoria expanded the palace. It contains a tiny office once used as a police station.
38. There is a 19th century time capsule under the base of Cleopatra's Needle - the 68ft, 3,450-year-old obelisk on the Embankment - containing a set of British currency, a railway guide, a Bible, and 12 portraits of "the prettiest English ladies".
39.Jarvis Cocker, singer of the pop band Pulp, wrote a song called 59 Lyndhurst Grove after being thrown out of a party at that address in Peckham.
40. Only one British Prime Minister out of 51 who have held the office since 1751, has ever been assassinated - Spencer Perceval was shot at the House of Commons in 1812.