| Castel Bolognese to Oberkirch | 340.80 mi (548.47 km) |
| Castel Bolognese to Obernburg am Main | 401.53 mi (646.21 km) |
| Castel Bolognese to Obernkirchen | 562.84 mi (905.80 km) |
| Castel Bolognese to Oberschleissheim | 271.99 mi (437.73 km) |
| Castel Bolognese to Oberstdorf | 225.87 mi (363.51 km) |
| Castel Bolognese to Obertraubling | 321.69 mi (517.71 km) |
| Castel Bolognese to Obertshausen | 420.91 mi (677.39 km) |
| Castel Bolognese to Oberursel | 433.79 mi (698.12 km) |
| Castel Bolognese to Ochsenfurt | 377.42 mi (607.39 km) |
| Castel Bolognese to Ochsenhausen | 274.16 mi (441.21 km) |
| Castel Bolognese to Ochtrup | 584.56 mi (940.76 km) |
| Castel Bolognese to Odenthal | 512.42 mi (824.65 km) |
| Castel Bolognese to Oelde | 545.82 mi (878.41 km) |
| Castel Bolognese to Oelsnitz | 421.82 mi (678.85 km) |
| Castel Bolognese to Oer-Erkenschwick | 547.86 mi (881.70 km) |
