Circuit de Monaco downhill again to a double right-hander called "Portier," named after region of Monaco, before heading into the famous tunnel, a unique feature of a Formula One circuit. (Until 2009 only one other circuit, Detroit in 1982–88, featured a tunnel, but the F1 series now includes racing at the Yas Marina Circuit in Abu Dhabi, which presents a shorter tunnel at the exit of the pit lane.) As well as the change of light making visibility poor, a car can lose 20–30% of its downforce due to the unique aerodynamic properties of the tunnel. The tunnel also presents a unique problem
Circuit des Nations Geneva, Switzerland – July 21, 1946 44 laps of the urban race track (short version) of , or , at an average speed of . FIA Formula 2, non championship race, Circuit des Nations, Geneva, Switzerland – May 2, 1948 70 laps of the urban race-track (short version) , or , at an average speed of . FIA Formula 1, non championship race, Circuit des Nations, Geneva, Switzerland – May 2, 1948 80 laps of the urban race-track (short version) or , at an average speed of . FIA Formula 2, non championship race, Circuit des Nations, Geneva, Switzerland –