| Castelo Branco to Octeville | 735.72 mi (1,184.02 km) |
| Castelo Branco to Oignies | 894.34 mi (1,439.30 km) |
| Castelo Branco to Oissel | 781.11 mi (1,257.07 km) |
| Castelo Branco to Olivet | 725.96 mi (1,168.32 km) |
| Castelo Branco to Ollioules | 727.09 mi (1,170.14 km) |
| Castelo Branco to Olonne-sur-Mer | 546.29 mi (879.17 km) |
| Castelo Branco to Oloron-Sainte-Marie | 426.02 mi (685.61 km) |
| Castelo Branco to Onet Village | 604.83 mi (973.38 km) |
| Castelo Branco to Onnaing | 906.98 mi (1,459.64 km) |
| Castelo Branco to Orange | 698.28 mi (1,123.78 km) |
| Castelo Branco to Orchies | 901.57 mi (1,450.93 km) |
| Castelo Branco to Orleans | 728.17 mi (1,171.87 km) |
| Castelo Branco to Orly | 785.98 mi (1,264.91 km) |
| Castelo Branco to Ormesson-sur-Marne | 792.57 mi (1,275.53 km) |
| Castelo Branco to Orsay | 777.39 mi (1,251.09 km) |
