| Mountain Ash to Orbetello | 934.62 mi (1,504.13 km) |
| Mountain Ash to Oria | 1,261.37 mi (2,029.98 km) |
| Mountain Ash to Oristano | 994.50 mi (1,600.49 km) |
| Mountain Ash to Orta Nova | 1,149.74 mi (1,850.34 km) |
| Mountain Ash to Orte | 974.25 mi (1,567.90 km) |
| Mountain Ash to Ortona | 1,052.25 mi (1,693.43 km) |
| Mountain Ash to Orvieto | 951.67 mi (1,531.57 km) |
| Mountain Ash to Orzinuovi | 745.98 mi (1,200.54 km) |
| Mountain Ash to Osimo | 964.98 mi (1,552.99 km) |
| Mountain Ash to Ospitaletto | 744.30 mi (1,197.84 km) |
| Mountain Ash to Ostuni | 1,248.19 mi (2,008.77 km) |
| Mountain Ash to Ottaviano | 1,129.25 mi (1,817.34 km) |
| Mountain Ash to Ovada | 735.85 mi (1,184.23 km) |
| Mountain Ash to Ozieri | 966.41 mi (1,555.28 km) |
| Mountain Ash to Paceco | 1,221.26 mi (1,965.42 km) |
