| Round Rock to Olivares | 5,051.34 mi (8,129.35 km) |
| Round Rock to Olivenza | 4,966.97 mi (7,993.56 km) |
| Round Rock to Olot | 5,305.52 mi (8,538.41 km) |
| Round Rock to Onate | 5,057.57 mi (8,139.36 km) |
| Round Rock to Onda | 5,254.00 mi (8,455.50 km) |
| Round Rock to Onteniente | 5,275.30 mi (8,489.78 km) |
| Round Rock to Orihuela | 5,283.32 mi (8,502.68 km) |
| Round Rock to Osuna | 5,108.71 mi (8,221.68 km) |
| Round Rock to Ourense | 4,826.90 mi (7,768.15 km) |
| Round Rock to Oviedo | 4,891.82 mi (7,872.63 km) |
| Round Rock to Paiporta | 5,264.32 mi (8,472.11 km) |
| Round Rock to Pajara | 4,903.09 mi (7,890.76 km) |
| Round Rock to Palafolls | 5,334.70 mi (8,585.37 km) |
| Round Rock to Palafrugell | 5,344.62 mi (8,601.34 km) |
| Round Rock to Palamos | 5,345.56 mi (8,602.85 km) |
