| Castrop-Rauxel to Oestrich-Winkel | 111.18 mi (178.92 km) |
| Castrop-Rauxel to Offenburg | 214.79 mi (345.66 km) |
| Castrop-Rauxel to Oftersheim | 160.57 mi (258.42 km) |
| Castrop-Rauxel to Ohrdruf | 156.10 mi (251.21 km) |
| Castrop-Rauxel to Ohringen | 188.71 mi (303.70 km) |
| Castrop-Rauxel to Olbernhau | 267.96 mi (431.23 km) |
| Castrop-Rauxel to Olching | 291.97 mi (469.87 km) |
| Castrop-Rauxel to Oldenburg | 116.45 mi (187.42 km) |
| Castrop-Rauxel to Oldenburg in Holstein | 241.13 mi (388.06 km) |
| Castrop-Rauxel to Olfen | 11.87 mi (19.10 km) |
| Castrop-Rauxel to Olpe | 43.08 mi (69.34 km) |
| Castrop-Rauxel to Olsberg | 52.10 mi (83.84 km) |
| Castrop-Rauxel to Oranienburg | 264.32 mi (425.38 km) |
| Castrop-Rauxel to Ortenberg | 111.95 mi (180.17 km) |
| Castrop-Rauxel to Oschatz | 250.00 mi (402.33 km) |
