| Siena to Octeville | 754.08 mi (1,213.57 km) |
| Siena to Oignies | 630.92 mi (1,015.36 km) |
| Siena to Oissel | 640.79 mi (1,031.25 km) |
| Siena to Olivet | 553.05 mi (890.05 km) |
| Siena to Ollioules | 276.33 mi (444.72 km) |
| Siena to Olonne-sur-Mer | 677.52 mi (1,090.36 km) |
| Siena to Oloron-Sainte-Marie | 600.28 mi (966.06 km) |
| Siena to Onet Village | 441.19 mi (710.02 km) |
| Siena to Onnaing | 609.31 mi (980.58 km) |
| Siena to Orange | 330.42 mi (531.76 km) |
| Siena to Orchies | 623.94 mi (1,004.14 km) |
| Siena to Orleans | 554.10 mi (891.74 km) |
| Siena to Orly | 568.86 mi (915.50 km) |
| Siena to Ormesson-sur-Marne | 565.45 mi (910.01 km) |
| Siena to Orsay | 574.38 mi (924.37 km) |
