| Constanta to Oberkirch | 1,021.83 mi (1,644.48 km) |
| Constanta to Obernburg am Main | 994.86 mi (1,601.06 km) |
| Constanta to Obernkirchen | 1,053.41 mi (1,695.30 km) |
| Constanta to Oberschleissheim | 861.25 mi (1,386.05 km) |
| Constanta to Oberstdorf | 909.87 mi (1,464.30 km) |
| Constanta to Obertraubling | 847.35 mi (1,363.68 km) |
| Constanta to Obertshausen | 1,012.33 mi (1,629.18 km) |
| Constanta to Oberursel | 1,025.86 mi (1,650.97 km) |
| Constanta to Ochsenfurt | 951.52 mi (1,531.33 km) |
| Constanta to Ochsenhausen | 931.99 mi (1,499.90 km) |
| Constanta to Ochtrup | 1,127.06 mi (1,813.83 km) |
| Constanta to Odenthal | 1,103.64 mi (1,776.13 km) |
| Constanta to Oelde | 1,079.73 mi (1,737.65 km) |
| Constanta to Oelsnitz | 881.53 mi (1,418.68 km) |
| Constanta to Oer-Erkenschwick | 1,111.25 mi (1,788.38 km) |
