| Ostrow Mazowiecka to Orbetello | 869.87 mi (1,399.93 km) |
| Ostrow Mazowiecka to Oria | 873.21 mi (1,405.29 km) |
| Ostrow Mazowiecka to Oristano | 1,090.06 mi (1,754.28 km) |
| Ostrow Mazowiecka to Orta Nova | 843.50 mi (1,357.48 km) |
| Ostrow Mazowiecka to Orte | 839.00 mi (1,350.23 km) |
| Ostrow Mazowiecka to Ortona | 801.17 mi (1,289.36 km) |
| Ostrow Mazowiecka to Orvieto | 830.20 mi (1,336.07 km) |
| Ostrow Mazowiecka to Orzinuovi | 742.86 mi (1,195.51 km) |
| Ostrow Mazowiecka to Osimo | 750.49 mi (1,207.80 km) |
| Ostrow Mazowiecka to Ospitaletto | 730.36 mi (1,175.39 km) |
| Ostrow Mazowiecka to Ostuni | 857.99 mi (1,380.80 km) |
| Ostrow Mazowiecka to Ottaviano | 895.99 mi (1,441.95 km) |
| Ostrow Mazowiecka to Ovada | 824.01 mi (1,326.12 km) |
| Ostrow Mazowiecka to Ozieri | 1,038.67 mi (1,671.57 km) |
| Ostrow Mazowiecka to Paceco | 1,117.55 mi (1,798.52 km) |
