The Greek Revival façade facing Great Russell Street is a characteristic building of Sir Robert Smirke, with 44 columns in the Ionic order 45 ft (14 m) high, closely based on those of the temple of Athena Polias at Priene in Asia Minor.
The pediment over the main entrance is decorated by sculptures by Sir Richard Westmacott depicting The Progress of Civilisation, consisting of fifteen allegorical figures, installed in 1852.

The construction commenced around the courtyard with the East Wing (The King's Library) in 1823–1828, followed by the North Wing in 1833–1838, which originally housed among other galleries a reading room, now the Wellcome Gallery.
Work was also progressing on the northern half of the West Wing (The Egyptian Sculpture Gallery) 1826–1831, with Montagu House demolished in 1842 to make room for the final part of the West Wing, completed in 1846, and the South Wing with its great colonnade, initiated in 1843 and completed in 1847, when the Front Hall and Great Staircase were opened to the public.
The museum is faced with Portland stone, but the perimeter walls and other parts of the building were built using Haytor granite from Dartmoor in South Devon, transported via the unique Haytor Granite Tramway.

In 1846 Robert Smirke was replaced as the museum's architect by his brother Sydney Smirke, whose major addition was the Round Reading Room 1854–1857; at 140 feet (43 m) in diameter it was then the second widest dome in the world, the Pantheon in Rome being slightly wider.

The next major addition was the White Wing 1882–1884 added behind the eastern end of the South Front, the architect being Sir John Taylor.

In 1895, Parliament gave the museum trustees a loan of £200,000 to purchase from the Duke of Bedford all 69 houses which backed onto the museum building in the five surrounding streets – Great Russell Street, Montague Street, Montague Place, Bedford Square and Bloomsbury Street.
The trustees planned to demolish these houses and to build around the west, north and east sides of the museum new galleries that would completely fill the block on which the museum stands.
The architect Sir John James Burnet was petitioned to put forward ambitious long-term plans to extend the building on all three sides.
Most of the houses in Montague Place were knocked down a few years after the sale.
Of this grand plan only the Edward VII galleries in the centre of the North Front were ever constructed, these were built 1906–14 to the design by J.J. Burnet, and opened by King George V and Queen Mary in 1914.
They now house the museum's collections of Prints and Drawings and Oriental Antiquities.
There was not enough money to put up more new buildings, and so the houses in the other streets are nearly all still standing.

The Duveen Gallery, sited to the west of the Egyptian, Greek & Assyrian sculpture galleries, was designed to house the Elgin Marbles by the American Beaux-Arts architect John Russell Pope.
Although completed in 1938, it was hit by a bomb in 1940 and remained semi-derelict for 22 years, before reopening in 1962.
Other areas damaged during World War II bombing included: in September 1940 two unexploded bombs hit the Edward VII galleries, the King's Library received a direct hit from a high explosive bomb, incendiaries fell on the dome of the Round Reading Room but did little damage; on the night of 10 to 11 May 1941 several incendiaries fell on the south-west corner of the museum, destroying the book stack and 150,000 books in the courtyard and the galleries around the top of the Great Staircase – this damage was not fully repaired until the early 1960s.

The Queen Elizabeth II Great Court is a covered square at the centre of the British Museum designed by the engineers Buro Happold and the architects Foster and Partners.
The Great Court opened in December 2000 and is the largest covered square in Europe.
The roof is a glass and steel construction, built by an Austrian steelwork company, with 1,656 uniquely shaped panes of glass.
At the centre of the Great Court is the Reading Room vacated by the British Library,
The Greek Revival façade facing Great Russell Street is a characteristic building of Sir Robert Smirke, with 44 columns in the Ionic order 45 ft (14 m) high, closely based on those of the temple of Athena Polias at Priene in Asia Minor. The pediment over the main entrance is decorated by sculptures by Sir Richard Westmacott depicting The Progress of Civilisation, consisting of fifteen allegorical figures, installed in 1852.
The construction commenced around the courtyard with the East Wing (The King's Library) in 1823–1828, followed by the North Wing in 1833–1838, which originally housed among other galleries a reading room, now the Wellcome Gallery. Work was also progressing on the northern half of the West Wing (The Egyptian Sculpture Gallery) 1826–1831, with Montagu House demolished in 1842 to make room for the final part of the West Wing, completed in 1846, and the South Wing with its great colonnade, initiated in 1843 and completed in 1847, when the Front Hall and Great Staircase were opened to the public. The museum is faced with Portland stone, but the perimeter walls and other parts of the building were built using Haytor granite from Dartmoor in South Devon, transported via the unique Haytor Granite Tramway.
In 1846 Robert Smirke was replaced as the museum's architect by his brother Sydney Smirke, whose major addition was the Round Reading Room 1854–1857; at 140 feet (43 m) in diameter it was then the second widest dome in the world, the Pantheon in Rome being slightly wider.
The next major addition was the White Wing 1882–1884 added behind the eastern end of the South Front, the architect being Sir John Taylor.
In 1895, Parliament gave the museum trustees a loan of £200,000 to purchase from the Duke of Bedford all 69 houses which backed onto the museum building in the five surrounding streets – Great Russell Street, Montague Street, Montague Place, Bedford Square and Bloomsbury Street. The trustees planned to demolish these houses and to build around the west, north and east sides of the museum new galleries that would completely fill the block on which the museum stands. The architect Sir John James Burnet was petitioned to put forward ambitious long-term plans to extend the building on all three sides. Most of the houses in Montague Place were knocked down a few years after the sale. Of this grand plan only the Edward VII galleries in the centre of the North Front were ever constructed, these were built 1906–14 to the design by J.J. Burnet, and opened by King George V and Queen Mary in 1914. They now house the museum's collections of Prints and Drawings and Oriental Antiquities. There was not enough money to put up more new buildings, and so the houses in the other streets are nearly all still standing.
The Duveen Gallery, sited to the west of the Egyptian, Greek & Assyrian sculpture galleries, was designed to house the Elgin Marbles by the American Beaux-Arts architect John Russell Pope. Although completed in 1938, it was hit by a bomb in 1940 and remained semi-derelict for 22 years, before reopening in 1962. Other areas damaged during World War II bombing included: in September 1940 two unexploded bombs hit the Edward VII galleries, the King's Library received a direct hit from a high explosive bomb, incendiaries fell on the dome of the Round Reading Room but did little damage; on the night of 10 to 11 May 1941 several incendiaries fell on the south-west corner of the museum, destroying the book stack and 150,000 books in the courtyard and the galleries around the top of the Great Staircase – this damage was not fully repaired until the early 1960s.
The Queen Elizabeth II Great Court is a covered square at the centre of the British Museum designed by the engineers Buro Happold and the architects Foster and Partners. The Great Court opened in December 2000 and is the largest covered square in Europe. The roof is a glass and steel construction, built by an Austrian steelwork company, with 1,656 uniquely shaped panes of glass. At the centre of the Great Court is the Reading Room vacated by the British Library,
British Museum