After George IV moved the mews to Buckingham Palace, the area was redeveloped by John Nash, but progress was slow after his death, and the square did not open until 1844.

A number of commemorative statues and sculptures occupy the square, but the Fourth Plinth, left empty since 1840, has been host to contemporary art since 1999.

The square has been used for community gatherings and political demonstrations, including Bloody Sunday in 1887, the culmination of the first Aldermaston March, anti-war protests, and campaigns against climate change.

[8] The square contains a large central area with roadways on three sides and a terrace to the north, in front of the National Gallery.

[9] Originally having roadways on all four sides, traffic travelled in both directions around the square until a one-way clockwise gyratory system was introduced on 26 April 1926.

[22] In 1826 the Commissioners of Woods, Forests and Land Revenues instructed John Nash to draw up plans for clearing a large area south of Kent's stable block, and as far east as St Martin's Lane.

His plans left open the whole area of what became Trafalgar Square, except for a block in the centre, which he reserved for a new building for the Royal Academy of Arts.

[25] Around 1835, it was decided that the square would be named after the Battle of Trafalgar as suggested by architect George Ledwell Taylor, commemorating Nelson's victory over the French and Spanish in 1805 during the Napoleonic Wars.

[23][28] For Barry, as for Wilkins, a major consideration was increasing the visual impact of the National Gallery, which had been widely criticised for its lack of grandeur.

In 1838 a Nelson Memorial Committee had approached the government proposing that a monument to the victory of Trafalgar, funded by public subscription, should be erected in the square.

A competition was held and won by the architect William Railton, who proposed a 218-foot-3-inch (66.52 m) Corinthinan column topped by a statue of Nelson and guarded by four sculpted lions.

In July 1840, when its foundations had been laid, he told a parliamentary select committee that "it would in my opinion be desirable that the area should be wholly free from all insulated objects of art".

[28] In 1940 the Nazi SS developed secret plans to transfer Nelson's Column to Berlin[b] after an expected German invasion, as related by Norman Longmate in If Britain Had Fallen (1972).

The scheme was initiated by the Royal Society of Arts and continued by the Fourth Plinth Commission, appointed by the Mayor of London.

[57] On the south side of Trafalgar Square, on the site of the original Charing Cross, is a bronze equestrian statue of Charles I by Hubert Le Sueur.

Sculpted by William Calder Marshall, it showed Jenner sitting in a chair in a relaxed pose, and was inaugurated at a ceremony presided over by Prince Albert.

[64] In 1841, following suggestions from the local paving board, Barry agreed that two fountains should be installed to counteract the effects of reflected heat and glare from the asphalt surface.

[70] The desirability of the birds' presence was contentious: their droppings disfigured the stonework and the flock, estimated at its peak to be 35,000, was considered a health hazard.

[75] In September 2007 Westminster City Council passed further bylaws banning feeding birds on the pedestrianised North Terrace and other pavements in the area.

Since 2014, New Year celebrations have been organised by the Greater London Authority in conjunction with the charity Unicef, who began ticketing the event to control crowd numbers.

[84] The square has become a social and political focus for visitors and Londoners, developing over its history from "an esplanade peopled with figures of national heroes, into the country's foremost place politique", as historian Rodney Mace has written.

[49] A ban on political rallies remained in effect until the 1880s, when the emerging Labour movement, particularly the Social Democratic Federation, began holding protests.

[85] The Campaign for Nuclear Disarmament's first Aldermaston March, protesting against the Atomic Weapons Establishment (AWE), began in the square in 1958.

[49] One of the first significant demonstrations of the modern era was held in the square on 19 September 1961 by the Committee of 100, which included the philosopher Bertrand Russell.

Crowds sang the French national anthem, La Marseillaise, and held banners in support of the city and country.

[95] The Royal British Legion holds a Silence in the Square event on Armistice Day, 11 November, in remembrance of those who died in war.

[97] In July 2020, two members of the protest group Animal Rebellion were arrested on suspicion for criminal damage after releasing red dye into the fountains.

In June 2002, 12,000 people gathered to watch England's FIFA World Cup quarter-final against Brazil on giant video screens which had been erected for the occasion.

It contains models of the National Gallery and Nelson's Column alongside miniature lions, fountains and double-decker buses.

[127] There is a life scale replica of the square in Bahria Town, Lahore, Pakistan where it is a tourist attraction and centre for local residents.