| Castel Bolognese to Oerlinghausen | 547.81 mi (881.62 km) |
| Castel Bolognese to Oestrich-Winkel | 431.21 mi (693.97 km) |
| Castel Bolognese to Offenburg | 340.74 mi (548.37 km) |
| Castel Bolognese to Oftersheim | 380.73 mi (612.72 km) |
| Castel Bolognese to Ohrdruf | 452.62 mi (728.43 km) |
| Castel Bolognese to Ohringen | 354.49 mi (570.49 km) |
| Castel Bolognese to Olbernhau | 444.52 mi (715.38 km) |
| Castel Bolognese to Olching | 269.30 mi (433.40 km) |
| Castel Bolognese to Oldenburg | 631.21 mi (1,015.83 km) |
| Castel Bolognese to Oldenburg in Holstein | 691.00 mi (1,112.05 km) |
| Castel Bolognese to Olfen | 550.27 mi (885.58 km) |
| Castel Bolognese to Olpe | 498.18 mi (801.74 km) |
| Castel Bolognese to Olsberg | 509.58 mi (820.09 km) |
| Castel Bolognese to Oranienburg | 586.65 mi (944.12 km) |
| Castel Bolognese to Ortenberg | 436.52 mi (702.52 km) |
