| Piraeus to Oberkirch | 1,068.16 mi (1,719.03 km) |
| Piraeus to Obernburg am Main | 1,090.37 mi (1,754.79 km) |
| Piraeus to Obernkirchen | 1,212.24 mi (1,950.92 km) |
| Piraeus to Oberschleissheim | 935.05 mi (1,504.82 km) |
| Piraeus to Oberstdorf | 940.33 mi (1,513.32 km) |
| Piraeus to Obertraubling | 952.51 mi (1,532.91 km) |
| Piraeus to Obertshausen | 1,111.09 mi (1,788.12 km) |
| Piraeus to Oberursel | 1,125.83 mi (1,811.84 km) |
| Piraeus to Ochsenfurt | 1,051.63 mi (1,692.44 km) |
| Piraeus to Ochsenhausen | 981.47 mi (1,579.52 km) |
| Piraeus to Ochtrup | 1,265.00 mi (2,035.82 km) |
| Piraeus to Odenthal | 1,211.76 mi (1,950.14 km) |
| Piraeus to Oelde | 1,218.01 mi (1,960.20 km) |
| Piraeus to Oelsnitz | 1,030.02 mi (1,657.65 km) |
| Piraeus to Oer-Erkenschwick | 1,236.05 mi (1,989.23 km) |
