| Romulus to Oerlinghausen | 4,085.26 mi (6,574.59 km) |
| Romulus to Oestrich-Winkel | 4,129.79 mi (6,646.25 km) |
| Romulus to Offenburg | 4,182.41 mi (6,730.94 km) |
| Romulus to Oftersheim | 4,174.74 mi (6,718.59 km) |
| Romulus to Ohrdruf | 4,202.24 mi (6,762.85 km) |
| Romulus to Ohringen | 4,215.97 mi (6,784.95 km) |
| Romulus to Olbernhau | 4,303.64 mi (6,926.03 km) |
| Romulus to Olching | 4,323.08 mi (6,957.32 km) |
| Romulus to Oldenburg | 4,028.14 mi (6,482.66 km) |
| Romulus to Oldenburg in Holstein | 4,082.58 mi (6,570.27 km) |
| Romulus to Olfen | 4,046.54 mi (6,512.27 km) |
| Romulus to Olpe | 4,087.59 mi (6,578.34 km) |
| Romulus to Olsberg | 4,100.14 mi (6,598.54 km) |
| Romulus to Oranienburg | 4,220.93 mi (6,792.94 km) |
| Romulus to Ortenberg | 4,156.95 mi (6,689.96 km) |
