| Catonsville to Orbetello | 4,381.75 mi (7,051.75 km) |
| Catonsville to Oria | 4,734.52 mi (7,619.47 km) |
| Catonsville to Oristano | 4,351.34 mi (7,002.80 km) |
| Catonsville to Orta Nova | 4,619.14 mi (7,433.78 km) |
| Catonsville to Orte | 4,432.64 mi (7,133.65 km) |
| Catonsville to Ortona | 4,524.49 mi (7,281.46 km) |
| Catonsville to Orvieto | 4,411.50 mi (7,099.62 km) |
| Catonsville to Orzinuovi | 4,226.64 mi (6,802.13 km) |
| Catonsville to Osimo | 4,444.21 mi (7,152.27 km) |
| Catonsville to Ospitaletto | 4,227.58 mi (6,803.63 km) |
| Catonsville to Ostuni | 4,723.35 mi (7,601.50 km) |
| Catonsville to Ottaviano | 4,582.82 mi (7,375.33 km) |
| Catonsville to Ovada | 4,195.74 mi (6,752.39 km) |
| Catonsville to Ozieri | 4,346.75 mi (6,995.42 km) |
| Catonsville to Paceco | 4,602.06 mi (7,406.30 km) |
