| Castel Gandolfo to Oegstgeest | 816.67 mi (1,314.31 km) |
| Castel Gandolfo to Oirschot | 757.92 mi (1,219.75 km) |
| Castel Gandolfo to Oisterwijk | 765.06 mi (1,231.24 km) |
| Castel Gandolfo to Oldebroek | 803.96 mi (1,293.85 km) |
| Castel Gandolfo to Oldenzaal | 777.76 mi (1,251.69 km) |
| Castel Gandolfo to Ommen | 799.02 mi (1,285.90 km) |
| Castel Gandolfo to Oosterend | 835.71 mi (1,344.95 km) |
| Castel Gandolfo to Oosterhout | 776.14 mi (1,249.07 km) |
| Castel Gandolfo to Oosterwolde | 831.10 mi (1,337.53 km) |
| Castel Gandolfo to Oostzaan | 822.73 mi (1,324.05 km) |
| Castel Gandolfo to Opmeer | 837.52 mi (1,347.85 km) |
| Castel Gandolfo to Oss | 769.41 mi (1,238.25 km) |
| Castel Gandolfo to Oud-Beijerland | 796.64 mi (1,282.07 km) |
| Castel Gandolfo to Oudenbosch | 780.53 mi (1,256.15 km) |
| Castel Gandolfo to Oudewater | 798.10 mi (1,284.41 km) |
