| Castel Gandolfo to Novi di Modena | 234.53 mi (377.43 km) |
| Castel Gandolfo to Novi Ligure | 284.84 mi (458.41 km) |
| Castel Gandolfo to Nuoro | 199.18 mi (320.55 km) |
| Castel Gandolfo to Occhiobello | 225.85 mi (363.47 km) |
| Castel Gandolfo to Oderzo | 278.83 mi (448.73 km) |
| Castel Gandolfo to Oggiono | 323.85 mi (521.18 km) |
| Castel Gandolfo to Olbia | 173.28 mi (278.87 km) |
| Castel Gandolfo to Oleggio | 333.38 mi (536.52 km) |
| Castel Gandolfo to Olgiate Comasco | 333.97 mi (537.47 km) |
| Castel Gandolfo to Olgiate Olona | 327.87 mi (527.65 km) |
| Castel Gandolfo to Omegna | 355.23 mi (571.69 km) |
| Castel Gandolfo to Opera | 304.41 mi (489.90 km) |
| Castel Gandolfo to Oppeano | 256.27 mi (412.43 km) |
| Castel Gandolfo to Orbassano | 341.54 mi (549.65 km) |
| Castel Gandolfo to Orbetello | 87.95 mi (141.54 km) |
