| Castle Pines to Oerlinghausen | 4,967.90 mi (7,995.06 km) |
| Castle Pines to Oestrich-Winkel | 5,037.04 mi (8,106.34 km) |
| Castle Pines to Offenburg | 5,105.78 mi (8,216.95 km) |
| Castle Pines to Oftersheim | 5,085.61 mi (8,184.50 km) |
| Castle Pines to Ohrdruf | 5,086.70 mi (8,186.25 km) |
| Castle Pines to Ohringen | 5,123.91 mi (8,246.14 km) |
| Castle Pines to Olbernhau | 5,175.81 mi (8,329.66 km) |
| Castle Pines to Olching | 5,231.53 mi (8,419.34 km) |
| Castle Pines to Oldenburg | 4,899.70 mi (7,885.30 km) |
| Castle Pines to Oldenburg in Holstein | 4,927.30 mi (7,929.73 km) |
| Castle Pines to Olfen | 4,938.30 mi (7,947.43 km) |
| Castle Pines to Olpe | 4,984.82 mi (8,022.29 km) |
| Castle Pines to Olsberg | 4,990.50 mi (8,031.43 km) |
| Castle Pines to Oranienburg | 5,070.96 mi (8,160.93 km) |
| Castle Pines to Ortenberg | 5,055.12 mi (8,135.43 km) |
