| Round Rock to Octeville | 4,893.57 mi (7,875.45 km) |
| Round Rock to Oignies | 5,052.09 mi (8,130.56 km) |
| Round Rock to Oissel | 5,012.60 mi (8,067.01 km) |
| Round Rock to Olivet | 5,092.28 mi (8,195.23 km) |
| Round Rock to Ollioules | 5,419.37 mi (8,721.64 km) |
| Round Rock to Olonne-sur-Mer | 4,979.58 mi (8,013.86 km) |
| Round Rock to Oloron-Sainte-Marie | 5,133.98 mi (8,262.34 km) |
| Round Rock to Onet Village | 5,236.44 mi (8,427.23 km) |
| Round Rock to Onnaing | 5,078.23 mi (8,172.61 km) |
| Round Rock to Orange | 5,339.46 mi (8,593.03 km) |
| Round Rock to Orchies | 5,061.66 mi (8,145.95 km) |
| Round Rock to Orleans | 5,091.38 mi (8,193.79 km) |
| Round Rock to Orly | 5,083.93 mi (8,181.80 km) |
| Round Rock to Ormesson-sur-Marne | 5,088.44 mi (8,189.05 km) |
| Round Rock to Orsay | 5,077.13 mi (8,170.85 km) |
