Going to make this a little realistic:
1: Albert Park, Australia
2: Sepang, Malaysia
3: Sakhir, Bahrain
4: Yas Marina, Abu Dhabi
5: Motorland Aragon, Spain
6: Monte Carlo, Monaco
7: Istanbul Parlk, Turkey
8: Circuit de Gilles Villeneuve, Canada
9: Indianapolis Motor Speedway (Moto GP layout), United States*
10: Silverstone, UK
11: Nurburgring, Germany
12: Portimao/Estoril, Portugal (they look pretty similar to me anyway)
13: Hungaroring (modified for a bit more speed by cutting the chicane and having a diagonal straight from the middle of the final straight into the first of the U-bends), Hungary
14: Spa-Francorchamps, Belgium
15: Monza, Italy
16: Shanghai, China
17: Suzuka, Japan
18: Buenos Aires, Argentina
19: Interlagos, Brazil
*pending finding out what Austin looks like. And it would only let me draw it in straight lines, so apologies for it being messy.