| Welwyn Garden City to Octeville | 163.38 mi (262.94 km) |
| Welwyn Garden City to Oignies | 166.17 mi (267.43 km) |
| Welwyn Garden City to Oissel | 179.35 mi (288.63 km) |
| Welwyn Garden City to Olivet | 287.89 mi (463.32 km) |
| Welwyn Garden City to Ollioules | 661.38 mi (1,064.39 km) |
| Welwyn Garden City to Olonne-sur-Mer | 371.03 mi (597.11 km) |
| Welwyn Garden City to Oloron-Sainte-Marie | 595.34 mi (958.11 km) |
| Welwyn Garden City to Onet Village | 529.84 mi (852.69 km) |
| Welwyn Garden City to Onnaing | 191.45 mi (308.11 km) |
| Welwyn Garden City to Orange | 577.80 mi (929.88 km) |
| Welwyn Garden City to Orchies | 175.10 mi (281.79 km) |
| Welwyn Garden City to Orleans | 285.48 mi (459.44 km) |
| Welwyn Garden City to Orly | 240.40 mi (386.88 km) |
| Welwyn Garden City to Ormesson-sur-Marne | 240.97 mi (387.81 km) |
| Welwyn Garden City to Orsay | 239.09 mi (384.78 km) |
