| Castel Gandolfo to Smolyan | 621.47 mi (1,000.15 km) |
| Castel Gandolfo to Sofia | 549.93 mi (885.03 km) |
| Castel Gandolfo to Sopot | 621.85 mi (1,000.77 km) |
| Castel Gandolfo to Sozopol | 772.04 mi (1,242.49 km) |
| Castel Gandolfo to Sredets | 746.67 mi (1,201.65 km) |
| Castel Gandolfo to Stamboliyski | 610.73 mi (982.88 km) |
| Castel Gandolfo to Stara Zagora | 667.49 mi (1,074.22 km) |
| Castel Gandolfo to Svilengrad | 697.58 mi (1,122.64 km) |
| Castel Gandolfo to Svishtov | 657.08 mi (1,057.48 km) |
| Castel Gandolfo to Targovishte | 716.39 mi (1,152.92 km) |
| Castel Gandolfo to Teteven | 598.25 mi (962.78 km) |
| Castel Gandolfo to Troyan | 620.84 mi (999.14 km) |
| Castel Gandolfo to Tryavna | 660.40 mi (1,062.81 km) |
| Castel Gandolfo to Tutrakan | 723.56 mi (1,164.46 km) |
| Castel Gandolfo to Varna | 783.31 mi (1,260.62 km) |
