London. The UK's major national museum, with enormously rich and varied collections covering world history and culture: it has magnificent holdings in classical antiquities, medieval art, prints and drawings, and numerous other fields, and it formerly also housed the national library of manuscripts and printed books. It was established by Act of Parliament in 1753 when the government bought the collection of the physician and naturalist Sir Hans Sloane (1660–1753), consisting of ‘books, manuscripts, prints, drawings, pictures, medals, coins, seals, cameos and natural curiosities’, and opened in 1759. Initially the museum was housed in Montagu House, a large 17th-century mansion in Bloomsbury, and for nearly 50 years it was necessary to make formal application for admission. With the acquisition of Sir William Hamilton's collection of classical vases and antiquities (1772), a plethora of Egyptian antiquities (including the Rosetta Stone donated by George III) at the turn of the century, the Elgin Marbles (1816), the magnificent library of George III (1823), and many other bequests and purchases, the Museum became established as one of the world's greatest treasure houses. Montagu House was now too small for its purpose and it was demolished in the course of construction of the present huge structure (1823–47), one of the masterpieces of Greek Revival architecture. The architect was Sir Robert Smirke and the great circular Reading Room at the centre of the building, designed by Smirke's brother Sydney, was completed in 1857. There have subsequently been various other additions to the building. Originally the Museum's collections embraced natural history, and one of its greatest attractions was a stuffed giraffe in the entrance hall, but the holdings in this area were transferred to the Natural History Museum in South Kensington, which opened in 1881. The Department of Prints and Drawings was originally part of the Library, but it led a separate existence from 1808 onwards. It began with over 2,000 drawings from the Sloane collections, which included an album of Dürer's drawings. Among the most important acquisitions since was the Richard Payne Knight bequest (1824) of over 1,000 drawings, including 273 by Claude. It is now one of the largest and most comprehensive collections in the world, containing more than two million items. The British Museum Library (as it was formerly known) was reconstituted by Act of Parliament as part of the British Library in 1973, and has been transferred to a new building, near St Pancras Station, opened in 1997. The former open quadrangle around the museum's circular Reading Room has been transformed into a spectacular glass-roofed space known as the Great Court (opened 2000).