| Welwyn Garden City to Orbetello | 838.45 mi (1,349.35 km) |
| Welwyn Garden City to Oria | 1,151.14 mi (1,852.59 km) |
| Welwyn Garden City to Oristano | 922.99 mi (1,485.40 km) |
| Welwyn Garden City to Orta Nova | 1,041.99 mi (1,676.93 km) |
| Welwyn Garden City to Orte | 873.13 mi (1,405.16 km) |
| Welwyn Garden City to Ortona | 944.57 mi (1,520.13 km) |
| Welwyn Garden City to Orvieto | 850.44 mi (1,368.66 km) |
| Welwyn Garden City to Orzinuovi | 639.21 mi (1,028.71 km) |
| Welwyn Garden City to Osimo | 855.37 mi (1,376.59 km) |
| Welwyn Garden City to Ospitaletto | 636.00 mi (1,023.54 km) |
| Welwyn Garden City to Ostuni | 1,137.34 mi (1,830.37 km) |
| Welwyn Garden City to Ottaviano | 1,027.21 mi (1,653.13 km) |
| Welwyn Garden City to Ovada | 639.98 mi (1,029.95 km) |
| Welwyn Garden City to Ozieri | 889.78 mi (1,431.97 km) |
| Welwyn Garden City to Paceco | 1,137.04 mi (1,829.89 km) |
