<P> After the clearance, development progressed slowly . The National Gallery was built on the north side between 1832 and 1838 to a design by William Wilkins, and in 1837 the Treasury approved Wilkins' plan for the laying out of the square, but it was not put into effect . In April 1840, following Wilkins' death, new plans by Charles Barry were accepted, and construction started within weeks . 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 . He dealt with the complex sloping site by excavating the main area to the level of the footway between Cockspur Street and the Strand, and constructing a 15 - foot (4.6 m) high balustraded terrace with a roadway on the north side, and steps at each end leading to the main level . Wilkins had proposed a similar solution with a central flight of steps . Plinths were provided for sculpture and pedestals for lighting . All the stonework was of Aberdeen granite . In 1841 it was decided that two fountains should be included in the layout . The estimated budget, excluding paving and sculptures, was £ 11,000 . The earth removed was used to level Green Park . The square was originally surfaced with tarmacadam, which was replaced with stone in the 1920s . </P> <P> Trafalgar Square was opened to the public on 1 May 1844 . </P> <P> Nelson's Column was planned independently of Barry's work . In 1838 a Nelson Memorial Committee had approached the government proposing that a monument to the victor 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 feet 3 inches (66.52 m) Corinthinan column topped by a statue of Nelson and guarded by four sculpted lions . The design was approved, but received widespread objections from the public . Construction went ahead beginning in 1840 but with the height reduced to 145 feet 3 inches (44.27 m). The column was completed and the statue raised in November 1843 . </P> <P> The last of the bronze reliefs on the column's pedestals was not completed until May 1854, and the four lions, although part of the original design, were only added in 1867 . Each lion weighs seven tons . A hoarding remained around the base of Nelson's Column for some years and some of its upper scaffolding remained in place . Landseer, the sculptor, had asked for a lion that had died at the London Zoo to be brought to his studio . He took so long to complete sketches that its corpse began to decompose and some parts had to be improvised . The statues have paws that resemble cats more than lions . </P>

What do the four lions in trafalgar square represent
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