| Castel Gandolfo to Settimo Torinese | 338.72 mi (545.11 km) |
| Castel Gandolfo to Seveso | 321.34 mi (517.14 km) |
| Castel Gandolfo to Sezze | 27.39 mi (44.07 km) |
| Castel Gandolfo to Siano | 124.52 mi (200.40 km) |
| Castel Gandolfo to Siena | 127.70 mi (205.51 km) |
| Castel Gandolfo to Signa | 161.22 mi (259.45 km) |
| Castel Gandolfo to Silea | 270.58 mi (435.46 km) |
| Castel Gandolfo to Silvi Paese | 93.32 mi (150.19 km) |
| Castel Gandolfo to Sinalunga | 111.82 mi (179.96 km) |
| Castel Gandolfo to Siniscola | 173.77 mi (279.66 km) |
| Castel Gandolfo to Sinnai | 247.61 mi (398.49 km) |
| Castel Gandolfo to Siracusa | 352.45 mi (567.21 km) |
| Castel Gandolfo to Solaro | 321.19 mi (516.91 km) |
| Castel Gandolfo to Soliera | 224.20 mi (360.82 km) |
| Castel Gandolfo to Solofra | 130.40 mi (209.86 km) |
