Trafalgar Square, designed by Sir Charles Barry, was constructed in the 1840s on the site that was originally the Royal Mews for hawks and then royal stables.
Sir Charles Barry was also responsible for the Houses of Parliament.
The Square is named in honour of the British victory, led by Admiral Lord Nelson, at the Battle of Trafalgar in 1805.
National Gallery, on right of photo, over looks the square
On the north side of Trafalgar Square is the National Gallery.
It was founded in 1824 when George IV persuaded the government to purchase 38 major paintings, including works by Raphael and Rembrandt.
The National Gallery houses one of the biggest picture collections in the world.
To the west lies the West End, with its famous shops and hotels.
To the east is the Strand, which leads to the City of London.
In 1876 the Imperial Measures were set into the north terrace wall.
Surveyors can still check ‘Perches’, ‘Chains’ and other archaic measures against feet and yards.
When the central staircase leading to the National Gallery was added, the measures were relocated to the bottom steps.
Dominating the square is the 56 m (171 feet) column, Nelson's Column, with its 5.5m (18 feet) statue of Nelson on top. It was erected in 1843.
Nelson faces south, towards Whitehall, Westminster Abbey, the Houses of Parliament and the River Thames. South west is Admiralty Arch, the entrance to the wide ceremonial drive to Buckingham Palace called The Mall.
Nelson's column is guarded by four huge bronze lions sculpted by Sir Edwin Landseer in 1868.
They were made out of metal from guns that had been taken from old battleships.
In the southeast corner of Trafalgar Square is a small former police phone box which is famous for being the World's smallest police station.
In 1926 Scotland Yard cut out the inside of what was an old light drum and installed a light and a telephone line which the police could use to call for assistance. The phone had direct access to New Scotland Yard, the
head-quarters of the London Metropolitan police.
The lantern lamp on its roof is said to be from Nelson’s flagship Victory, although there is no evidence that this is true.
Today the police box is used as a broom cupboard for Westminster Council cleaners.
To the east of Trafalgar Square is the 18th century St Martin's-in-the-Fields church.
The first church built on this site in the 13th century stood 'in the fields' between the City and Westminster.
Many famous people have been buried at St Martin's including Nell Gwynn, mistress of Charles II , the painters William Hogarth and Joshua Reynolds and the renowned craftsman Thomas Chippendale.
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After visiting Trafalgar Square walk through Admiralty Arch and into the Mall. You can walk down the Mall to Buckingham Palace.