| Hardenberg to Oberkirch | 286.01 mi (460.28 km) |
| Hardenberg to Obernburg am Main | 217.77 mi (350.47 km) |
| Hardenberg to Obernkirchen | 107.42 mi (172.87 km) |
| Hardenberg to Oberschleissheim | 369.23 mi (594.21 km) |
| Hardenberg to Oberstdorf | 391.58 mi (630.18 km) |
| Hardenberg to Obertraubling | 347.27 mi (558.87 km) |
| Hardenberg to Obertshausen | 197.46 mi (317.78 km) |
| Hardenberg to Oberursel | 183.86 mi (295.89 km) |
| Hardenberg to Ochsenfurt | 250.96 mi (403.88 km) |
| Hardenberg to Ochsenhausen | 343.47 mi (552.76 km) |
| Hardenberg to Ochtrup | 34.75 mi (55.92 km) |
| Hardenberg to Odenthal | 108.08 mi (173.94 km) |
| Hardenberg to Oelde | 82.36 mi (132.55 km) |
| Hardenberg to Oelsnitz | 281.08 mi (452.36 km) |
| Hardenberg to Oer-Erkenschwick | 69.31 mi (111.55 km) |
