The Science Museum is part of the National Museum of Science and Industry and it is a major London tourist attraction. It now holds a collection of over 300,000 items, including such famous items as Stephenson’s Rocket, the oldest surviving steam locomotive, the first jet engine, a reconstruction of Francis Crick and James Watson’s model of DNA and the first prototype of the 10,000-year Clock of the Long Now. It also contains hundreds of interactive exhibits. A recent addition is the IMAX 3D Cinema showing science and nature documentaries, some of them in 3-D. Entrance has been free since 1 December 2001.