#4 Österreichring
Yes, like Hockenheim, this track is in the Formula One calendar today, but it has been modified for safety reasons. So much so that it is a completely different track than it used to be. The current Red Bull Ring was formerly known as the Österreichring and it was built in 1969.
Back then it had eight corners, but it got one more in 1977. The track went up and down in the Alps and offered a great challenge for the drivers. But it was very dangerous. It was dropped from the F1 calendar after the 1987 season for safety reasons. It made a comeback in 1997 (after modifications by Herman Tilke) and is now what we know as the Red Bull Ring.
Here's Satoru Nakajima storming through the old Österreichring in 1987.