| Greenford to Orbetello | 829.55 mi (1,335.03 km) |
| Greenford to Oria | 1,145.59 mi (1,843.66 km) |
| Greenford to Oristano | 910.06 mi (1,464.60 km) |
| Greenford to Orta Nova | 1,035.78 mi (1,666.92 km) |
| Greenford to Orte | 865.28 mi (1,392.54 km) |
| Greenford to Ortona | 938.28 mi (1,510.01 km) |
| Greenford to Orvieto | 842.60 mi (1,356.04 km) |
| Greenford to Orzinuovi | 632.40 mi (1,017.75 km) |
| Greenford to Osimo | 849.49 mi (1,367.13 km) |
| Greenford to Ospitaletto | 629.56 mi (1,013.18 km) |
| Greenford to Ostuni | 1,131.94 mi (1,821.69 km) |
| Greenford to Ottaviano | 1,019.68 mi (1,641.01 km) |
| Greenford to Ovada | 630.77 mi (1,015.13 km) |
| Greenford to Ozieri | 877.56 mi (1,412.30 km) |
| Greenford to Paceco | 1,126.20 mi (1,812.45 km) |
