| Harmanli to Oegstgeest | 1,225.10 mi (1,971.60 km) |
| Harmanli to Oirschot | 1,172.19 mi (1,886.45 km) |
| Harmanli to Oisterwijk | 1,178.59 mi (1,896.75 km) |
| Harmanli to Oldebroek | 1,180.60 mi (1,900.00 km) |
| Harmanli to Oldenzaal | 1,138.45 mi (1,832.15 km) |
| Harmanli to Ommen | 1,164.23 mi (1,873.64 km) |
| Harmanli to Oosterend | 1,194.29 mi (1,922.03 km) |
| Harmanli to Oosterhout | 1,193.62 mi (1,920.95 km) |
| Harmanli to Oosterwolde | 1,185.87 mi (1,908.48 km) |
| Harmanli to Oostzaan | 1,217.46 mi (1,959.31 km) |
| Harmanli to Opmeer | 1,223.83 mi (1,969.56 km) |
| Harmanli to Oss | 1,172.20 mi (1,886.48 km) |
| Harmanli to Oud-Beijerland | 1,216.45 mi (1,957.68 km) |
| Harmanli to Oudenbosch | 1,204.91 mi (1,939.11 km) |
| Harmanli to Oudewater | 1,204.75 mi (1,938.86 km) |
