Located in London, the British Library is the national library of the United Kingdom. Its collections are estimated between 170-200 million items, making it the largest library in the world by catalogued items. The British Library was part of the British Museum until 1973, with the passing of the British Library Act in 1972. It is currently located in on Euston Street in St. Pancras London, though the Reading Room remains in its original location at the British Museum.