| Trecastagni to Oerlinghausen | 1,039.20 mi (1,672.43 km) |
| Trecastagni to Oestrich-Winkel | 924.60 mi (1,488.00 km) |
| Trecastagni to Offenburg | 831.18 mi (1,337.66 km) |
| Trecastagni to Oftersheim | 874.19 mi (1,406.87 km) |
| Trecastagni to Ohrdruf | 937.46 mi (1,508.70 km) |
| Trecastagni to Ohringen | 847.38 mi (1,363.72 km) |
| Trecastagni to Olbernhau | 905.76 mi (1,457.69 km) |
| Trecastagni to Olching | 755.42 mi (1,215.73 km) |
| Trecastagni to Oldenburg | 1,122.16 mi (1,805.94 km) |
| Trecastagni to Oldenburg in Holstein | 1,169.70 mi (1,882.45 km) |
| Trecastagni to Olfen | 1,043.70 mi (1,679.67 km) |
| Trecastagni to Olpe | 991.62 mi (1,595.85 km) |
| Trecastagni to Olsberg | 1,002.09 mi (1,612.71 km) |
| Trecastagni to Oranienburg | 1,049.68 mi (1,689.30 km) |
| Trecastagni to Ortenberg | 929.02 mi (1,495.12 km) |
