The Circuit Bremgarten was a 7.28 km motorsport race track in Bern, Switzerland which formerly hosted the Swiss Grand Prix from 1933 to 1939 (Formula One, 1947 to 1954) and the Swiss motorcycle Grand Prix. Bremgarten was built as a motorcycle racing track in 1931 in the Bremgartenwald (Bremgarten forest) in the north of Bern. The circuit itself had no true straight, instead being a collection of high-speed corners. It hosted its first automobile race in 1934. From the outset, Bremgarten's tree-lined roads, often poor light conditions and changes in road surface made for what was acknowledged to be a very dangerous circuit, especially in the wet. Bremgarten has not hosted an official motorsport event since 1955, when spectator racing sports (with the exception of hillclimbing and rallying) were banned in Switzerland following the 1955 Le Mans disaster.