| Castro Valley to Oerlinghausen | 5,567.32 mi (8,959.73 km) |
| Castro Valley to Oestrich-Winkel | 5,657.35 mi (9,104.63 km) |
| Castro Valley to Offenburg | 5,739.37 mi (9,236.63 km) |
| Castro Valley to Oftersheim | 5,707.77 mi (9,185.76 km) |
| Castro Valley to Ohrdruf | 5,683.59 mi (9,146.85 km) |
| Castro Valley to Ohringen | 5,741.97 mi (9,240.81 km) |
| Castro Valley to Olbernhau | 5,757.83 mi (9,266.34 km) |
| Castro Valley to Olching | 5,846.53 mi (9,409.08 km) |
| Castro Valley to Oldenburg | 5,491.30 mi (8,837.39 km) |
| Castro Valley to Oldenburg in Holstein | 5,493.14 mi (8,840.36 km) |
| Castro Valley to Olfen | 5,547.33 mi (8,927.56 km) |
| Castro Valley to Olpe | 5,597.36 mi (9,008.08 km) |
| Castro Valley to Olsberg | 5,596.36 mi (9,006.47 km) |
| Castro Valley to Oranienburg | 5,636.10 mi (9,070.42 km) |
| Castro Valley to Ortenberg | 5,666.14 mi (9,118.78 km) |
