| Constanta to Nuth | 1,152.99 mi (1,855.56 km) |
| Constanta to Oegstgeest | 1,235.64 mi (1,988.57 km) |
| Constanta to Oirschot | 1,188.10 mi (1,912.07 km) |
| Constanta to Oisterwijk | 1,193.83 mi (1,921.28 km) |
| Constanta to Oldebroek | 1,184.02 mi (1,905.49 km) |
| Constanta to Oldenzaal | 1,139.96 mi (1,834.59 km) |
| Constanta to Ommen | 1,165.22 mi (1,875.25 km) |
| Constanta to Oosterend | 1,191.07 mi (1,916.85 km) |
| Constanta to Oosterhout | 1,209.12 mi (1,945.89 km) |
| Constanta to Oosterwolde | 1,182.05 mi (1,902.33 km) |
| Constanta to Oostzaan | 1,224.11 mi (1,970.02 km) |
| Constanta to Opmeer | 1,227.38 mi (1,975.28 km) |
| Constanta to Oss | 1,184.47 mi (1,906.21 km) |
| Constanta to Oud-Beijerland | 1,231.21 mi (1,981.43 km) |
| Constanta to Oudenbosch | 1,221.88 mi (1,966.42 km) |
