| Highlands Ranch to Orbetello | 5,507.97 mi (8,864.21 km) |
| Highlands Ranch to Oria | 5,831.81 mi (9,385.39 km) |
| Highlands Ranch to Oristano | 5,534.29 mi (8,906.58 km) |
| Highlands Ranch to Orta Nova | 5,722.43 mi (9,209.36 km) |
| Highlands Ranch to Orte | 5,548.76 mi (8,929.87 km) |
| Highlands Ranch to Ortona | 5,624.91 mi (9,052.42 km) |
| Highlands Ranch to Orvieto | 5,526.20 mi (8,893.56 km) |
| Highlands Ranch to Orzinuovi | 5,318.80 mi (8,559.78 km) |
| Highlands Ranch to Osimo | 5,536.06 mi (8,909.43 km) |
| Highlands Ranch to Ospitaletto | 5,316.19 mi (8,555.59 km) |
| Highlands Ranch to Ostuni | 5,817.89 mi (9,362.99 km) |
| Highlands Ranch to Ottaviano | 5,703.77 mi (9,179.33 km) |
| Highlands Ranch to Ovada | 5,309.82 mi (8,545.32 km) |
| Highlands Ranch to Ozieri | 5,517.13 mi (8,878.96 km) |
| Highlands Ranch to Paceco | 5,778.25 mi (9,299.20 km) |
