| Castel Gandolfo to Oerlinghausen | 730.50 mi (1,175.63 km) |
| Castel Gandolfo to Oestrich-Winkel | 612.27 mi (985.35 km) |
| Castel Gandolfo to Offenburg | 517.93 mi (833.54 km) |
| Castel Gandolfo to Oftersheim | 562.08 mi (904.58 km) |
| Castel Gandolfo to Ohrdruf | 634.05 mi (1,020.40 km) |
| Castel Gandolfo to Ohringen | 537.00 mi (864.21 km) |
| Castel Gandolfo to Olbernhau | 617.15 mi (993.21 km) |
| Castel Gandolfo to Olching | 450.60 mi (725.17 km) |
| Castel Gandolfo to Oldenburg | 813.90 mi (1,309.84 km) |
| Castel Gandolfo to Oldenburg in Holstein | 871.10 mi (1,401.91 km) |
| Castel Gandolfo to Olfen | 732.15 mi (1,178.29 km) |
| Castel Gandolfo to Olpe | 680.04 mi (1,094.42 km) |
| Castel Gandolfo to Olsberg | 692.15 mi (1,113.91 km) |
| Castel Gandolfo to Oranienburg | 761.03 mi (1,224.76 km) |
| Castel Gandolfo to Ortenberg | 619.12 mi (996.38 km) |
