| Isernia to Octeville | 943.76 mi (1,518.83 km) |
| Isernia to Oignies | 814.45 mi (1,310.72 km) |
| Isernia to Oissel | 829.66 mi (1,335.21 km) |
| Isernia to Olivet | 742.83 mi (1,195.48 km) |
| Isernia to Ollioules | 441.16 mi (709.98 km) |
| Isernia to Olonne-sur-Mer | 862.90 mi (1,388.70 km) |
| Isernia to Oloron-Sainte-Marie | 764.41 mi (1,230.20 km) |
| Isernia to Onet Village | 618.18 mi (994.87 km) |
| Isernia to Onnaing | 791.71 mi (1,274.13 km) |
| Isernia to Orange | 508.27 mi (817.98 km) |
| Isernia to Orchies | 806.90 mi (1,298.58 km) |
| Isernia to Orleans | 743.88 mi (1,197.16 km) |
| Isernia to Orly | 757.68 mi (1,219.37 km) |
| Isernia to Ormesson-sur-Marne | 754.08 mi (1,213.57 km) |
| Isernia to Orsay | 763.42 mi (1,228.61 km) |
