| Middlesex to Olivares | 3,582.26 mi (5,765.09 km) |
| Middlesex to Olivenza | 3,497.81 mi (5,629.18 km) |
| Middlesex to Olot | 3,848.77 mi (6,194.00 km) |
| Middlesex to Onate | 3,597.87 mi (5,790.21 km) |
| Middlesex to Onda | 3,788.81 mi (6,097.50 km) |
| Middlesex to Onteniente | 3,808.09 mi (6,128.53 km) |
| Middlesex to Orihuela | 3,815.14 mi (6,139.87 km) |
| Middlesex to Osuna | 3,639.58 mi (5,857.34 km) |
| Middlesex to Ourense | 3,361.15 mi (5,409.24 km) |
| Middlesex to Oviedo | 3,429.87 mi (5,519.85 km) |
| Middlesex to Paiporta | 3,798.10 mi (6,112.45 km) |
| Middlesex to Pajara | 3,474.02 mi (5,590.90 km) |
| Middlesex to Palafolls | 3,876.67 mi (6,238.90 km) |
| Middlesex to Palafrugell | 3,887.89 mi (6,256.96 km) |
| Middlesex to Palamos | 3,888.56 mi (6,258.03 km) |
