| Castel Gandolfo to Octeville | 876.43 mi (1,410.47 km) |
| Castel Gandolfo to Oignies | 758.43 mi (1,220.58 km) |
| Castel Gandolfo to Oissel | 765.43 mi (1,231.85 km) |
| Castel Gandolfo to Olivet | 674.51 mi (1,085.51 km) |
| Castel Gandolfo to Ollioules | 359.94 mi (579.27 km) |
| Castel Gandolfo to Olonne-sur-Mer | 786.50 mi (1,265.75 km) |
| Castel Gandolfo to Oloron-Sainte-Marie | 682.34 mi (1,098.12 km) |
| Castel Gandolfo to Onet Village | 538.63 mi (866.84 km) |
| Castel Gandolfo to Onnaing | 736.95 mi (1,186.01 km) |
| Castel Gandolfo to Orange | 429.46 mi (691.15 km) |
| Castel Gandolfo to Orchies | 751.54 mi (1,209.48 km) |
| Castel Gandolfo to Orleans | 675.71 mi (1,087.46 km) |
| Castel Gandolfo to Orly | 693.69 mi (1,116.38 km) |
| Castel Gandolfo to Ormesson-sur-Marne | 690.55 mi (1,111.33 km) |
| Castel Gandolfo to Orsay | 698.83 mi (1,124.66 km) |
