| Cascais to Orbetello | 1,110.09 mi (1,786.51 km) |
| Cascais to Oria | 1,439.77 mi (2,317.08 km) |
| Cascais to Oristano | 964.76 mi (1,552.64 km) |
| Cascais to Orta Nova | 1,337.29 mi (2,152.16 km) |
| Cascais to Orte | 1,169.74 mi (1,882.52 km) |
| Cascais to Ortona | 1,271.58 mi (2,046.41 km) |
| Cascais to Orvieto | 1,157.67 mi (1,863.09 km) |
| Cascais to Orzinuovi | 1,091.70 mi (1,756.92 km) |
| Cascais to Osimo | 1,232.99 mi (1,984.30 km) |
| Cascais to Ospitaletto | 1,101.52 mi (1,772.73 km) |
| Cascais to Ostuni | 1,436.15 mi (2,311.26 km) |
| Cascais to Ottaviano | 1,273.51 mi (2,049.51 km) |
| Cascais to Ovada | 1,015.73 mi (1,634.66 km) |
| Cascais to Ozieri | 986.80 mi (1,588.10 km) |
| Cascais to Paceco | 1,188.59 mi (1,912.85 km) |
