| Boulder to Castelfidardo | 5,523.40 mi (8,889.06 km) |
| Boulder to Castelfiorentino | 5,427.31 mi (8,734.40 km) |
| Boulder to Castelfranco di Sopra | 5,446.82 mi (8,765.81 km) |
| Boulder to Castelfranco di Sotto | 5,414.78 mi (8,714.25 km) |
| Boulder to Castelfranco Emilia | 5,381.22 mi (8,660.24 km) |
| Boulder to Castelfranco Veneto | 5,358.45 mi (8,623.60 km) |
| Boulder to Castellabate | 5,734.75 mi (9,229.19 km) |
| Boulder to Castellammare del Golfo | 5,775.08 mi (9,294.10 km) |
| Boulder to Castellammare di Stabia | 5,696.78 mi (9,168.09 km) |
| Boulder to Castellamonte | 5,226.58 mi (8,411.37 km) |
| Boulder to Castellana Grotte | 5,779.85 mi (9,301.77 km) |
| Boulder to Castellaneta | 5,785.00 mi (9,310.06 km) |
| Boulder to Castellanza | 5,257.03 mi (8,460.38 km) |
| Boulder to Castellarano | 5,373.37 mi (8,647.61 km) |
| Boulder to Castelleone | 5,302.39 mi (8,533.38 km) |
