| Castleton to Mangualde | 934.25 mi (1,503.53 km) |
| Castleton to Marco de Canavezes | 900.91 mi (1,449.87 km) |
| Castleton to Marinha Grande | 1,007.45 mi (1,621.34 km) |
| Castleton to Massama | 1,078.46 mi (1,735.61 km) |
| Castleton to Matosinhos | 909.06 mi (1,463.00 km) |
| Castleton to Mealhada | 958.37 mi (1,542.34 km) |
| Castleton to Melgaco | 840.84 mi (1,353.20 km) |
| Castleton to Melres | 912.26 mi (1,468.15 km) |
| Castleton to Mira | 959.17 mi (1,543.64 km) |
| Castleton to Miranda do Corvo | 975.60 mi (1,570.08 km) |
| Castleton to Mirandela | 867.86 mi (1,396.69 km) |
| Castleton to Mogadouro | 872.63 mi (1,404.36 km) |
| Castleton to Moimenta da Beira | 907.20 mi (1,460.00 km) |
| Castleton to Moita | 1,081.37 mi (1,740.30 km) |
| Castleton to Moncao | 847.01 mi (1,363.13 km) |
