British Museum Reading Room. This large reading room, located at the British Museum, Bloomsbury, London, UK, was the reading room of the British Library before the library moved to its current London location at St Pancras in 1997. The dome of the reading room is 43 metres across, and consists of segments mounted on a cast iron framework. The apex of the dome is 33 metres above the floor. Surrounding the room there are nearly 5 kilometres of bookcases and 40 kilometres of bookshelves. Construction of the reading room was completed in 1857. It has been used as an exhibition space since 2006.