I had the good fortune to race in the support race for four Formula 1 races driving Formula Atlantic (the US version of Formula 2) before the US Grand Prix in the Streets of Detroit in 1983, the Canadian Grand Prix in 1983 and again in 1988 and driving the Can-Am Series in 1984 before the US Grand Prix in Dallas. There is really nothing quite like the excitement of an F1 event.
To Jon's point, the race in Detroit was through the streets and included going through a tunnel. It was really something. I DNFed that day as I lunched my engine, but it was an event I'll never forget. It was made even more so, as it was my first race following a serious crash the previous September where I was very badly injured. The Formula Atlantic teams were paddocked in the Cobo Center with the F1 teams. My small team was set up only 20 feet away from the Ferrari Formula One team. I thought I had died and gone to heaven.