| Grevena to Oerlinghausen | 1,020.90 mi (1,642.98 km) |
| Grevena to Oestrich-Winkel | 945.38 mi (1,521.44 km) |
| Grevena to Offenburg | 881.44 mi (1,418.54 km) |
| Grevena to Oftersheim | 897.10 mi (1,443.75 km) |
| Grevena to Ohrdruf | 903.33 mi (1,453.77 km) |
| Grevena to Ohringen | 858.48 mi (1,381.58 km) |
| Grevena to Olbernhau | 828.83 mi (1,333.87 km) |
| Grevena to Olching | 750.84 mi (1,208.37 km) |
| Grevena to Oldenburg | 1,095.00 mi (1,762.24 km) |
| Grevena to Oldenburg in Holstein | 1,097.13 mi (1,765.65 km) |
| Grevena to Olfen | 1,046.00 mi (1,683.38 km) |
| Grevena to Olpe | 998.33 mi (1,606.66 km) |
| Grevena to Olsberg | 994.81 mi (1,600.99 km) |
| Grevena to Oranienburg | 956.90 mi (1,539.98 km) |
| Grevena to Ortenberg | 928.18 mi (1,493.75 km) |
