| Castelo Branco to Ifield | 856.39 mi (1,378.23 km) |
| Castelo Branco to Ilford | 888.86 mi (1,430.48 km) |
| Castelo Branco to Ilfracombe | 803.67 mi (1,293.38 km) |
| Castelo Branco to Ilkeston | 954.67 mi (1,536.39 km) |
| Castelo Branco to Ilkley | 1,010.20 mi (1,625.76 km) |
| Castelo Branco to Immingham | 1,012.49 mi (1,629.45 km) |
| Castelo Branco to Ince-in-Makerfield | 975.66 mi (1,570.17 km) |
| Castelo Branco to Inverness | 1,229.03 mi (1,977.94 km) |
| Castelo Branco to Inverurie | 1,228.26 mi (1,976.70 km) |
| Castelo Branco to Ipswich | 941.04 mi (1,514.46 km) |
| Castelo Branco to Irlam | 971.33 mi (1,563.21 km) |
| Castelo Branco to Irthlingborough | 924.03 mi (1,487.09 km) |
| Castelo Branco to Irvine | 1,099.62 mi (1,769.66 km) |
| Castelo Branco to Islington | 884.38 mi (1,423.27 km) |
| Castelo Branco to Iver | 875.36 mi (1,408.76 km) |
