Catesby Tunnel is a disused railway tunnel in Northamptonshire on the route of the former Great Central Main Line. Its northern portal is about 1,100 yards (1,000 m) south of Catesby Viaduct and 250 yards (230 m) west of Upper Catesby, with the tunnel ending at Charwelton to the south. In terms of both length and gauge, Catesby Tunnel is unusually large, at 27 feet (8.2 m) wide, 25 feet 6 inches (7.8 m) high, and 2,997 yards (2.7 km; 1.7 mi) long.[1]
The tunnel was completed in 1897, and was closed in 1966 when the line was made redundant by British Rail. After lying abandoned and flooded for over 50 years, proposals were granted in 2017 for the conversion of the wide, straight tunnel into an aerodynamic test facility for road and race cars.