Well there aren’t very much real circuits at all; but i managed to found this monza racetrack; you fill find the fixed map in the comment of the second page of the thread: https://www.beamng.com/threads/autodromo-nazionale-monza-1988.4010/
Here are some that i know: 1. Pikes Peak 2. Road Atlanta 3. Lime Rock Park 4. Aegean race track 5. Lakeside Raceway 6. Agassiz speedway