The Doughnut is the nickname given (due to its resemblance to a doughnut) to the headquarters of the Government Communications Headquarters (GCHQ), a British cryptography and intelligence agency. It is located on a 71 hectares (176 acres) site in Benhall, in the suburbs of Cheltenham, Gloucestershire, in South West England. The Doughnut accommodates 5,500 employees; GCHQ is the largest single employer in Gloucestershire. Built to modernise and consolidate GCHQ's multiple buildings in Cheltenham, the Doughnut was completed in 2003, with GCHQ staff moving in the same year, and fully moved into the building in 2004.The Doughnut was too small for the number of staff at its completion, and a second building in a secret and undisclosed location in the 'Gloucestershire area' now also accommodates staff from GCHQ. The Doughnut is surrounded by car and bicycle parking in concentric rings, and is well protected by security fencing, guards, and CCTV systems.
The construction of the building was financed by a private finance initiative, and construction costs were greatly increased after difficulties in transferring computer infrastructure to the building. The building is modern in design, and built primarily from steel, aluminium, and stone. GCHQ management aspired for the building to be as well known internationally as the Pentagon.