JET, the Joint European Torus, is the largest nuclear fusion experimental reactor yet built. The reactor is situated on an old Navy airfield near Culham, Oxfordshire, in the UK: the construction of the buildings which house the project was undertaken by Tarmac Construction, starting in 1978 with the Torus Hall being completed in January 1982. Construction of the experiment itself began immediately after the completion of the Torus Hall, with the first experiments beginning in 1983.