| Castel Gandolfo to Oberkirch | 518.84 mi (834.99 km) |
| Castel Gandolfo to Obernburg am Main | 584.02 mi (939.89 km) |
| Castel Gandolfo to Obernkirchen | 745.42 mi (1,199.64 km) |
| Castel Gandolfo to Oberschleissheim | 452.42 mi (728.11 km) |
| Castel Gandolfo to Oberstdorf | 408.26 mi (657.03 km) |
| Castel Gandolfo to Obertraubling | 499.33 mi (803.59 km) |
| Castel Gandolfo to Obertshausen | 603.24 mi (970.81 km) |
| Castel Gandolfo to Oberursel | 615.93 mi (991.24 km) |
| Castel Gandolfo to Ochsenfurt | 560.03 mi (901.28 km) |
| Castel Gandolfo to Ochsenhausen | 456.54 mi (734.74 km) |
| Castel Gandolfo to Ochtrup | 766.57 mi (1,233.68 km) |
| Castel Gandolfo to Odenthal | 693.24 mi (1,115.67 km) |
| Castel Gandolfo to Oelde | 728.35 mi (1,172.17 km) |
| Castel Gandolfo to Oelsnitz | 599.47 mi (964.76 km) |
| Castel Gandolfo to Oer-Erkenschwick | 729.53 mi (1,174.07 km) |
