| Niederkassel to Oria | 875.68 mi (1,409.27 km) |
| Niederkassel to Oristano | 757.61 mi (1,219.25 km) |
| Niederkassel to Orta Nova | 775.07 mi (1,247.36 km) |
| Niederkassel to Orte | 630.33 mi (1,014.42 km) |
| Niederkassel to Ortona | 680.84 mi (1,095.70 km) |
| Niederkassel to Orvieto | 608.59 mi (979.43 km) |
| Niederkassel to Orzinuovi | 397.37 mi (639.51 km) |
| Niederkassel to Osimo | 589.89 mi (949.34 km) |
| Niederkassel to Ospitaletto | 389.48 mi (626.81 km) |
| Niederkassel to Ostuni | 860.65 mi (1,385.08 km) |
| Niederkassel to Ottaviano | 775.37 mi (1,247.83 km) |
| Niederkassel to Ovada | 433.33 mi (697.38 km) |
| Niederkassel to Ozieri | 713.24 mi (1,147.85 km) |
| Niederkassel to Paceco | 926.92 mi (1,491.73 km) |
| Niederkassel to Pachino | 1,052.57 mi (1,693.94 km) |
