| Niederkassel to Smolyan | 1,054.16 mi (1,696.51 km) |
| Niederkassel to Sofia | 950.29 mi (1,529.34 km) |
| Niederkassel to Sopot | 1,007.02 mi (1,620.65 km) |
| Niederkassel to Sozopol | 1,133.93 mi (1,824.88 km) |
| Niederkassel to Sredets | 1,116.72 mi (1,797.20 km) |
| Niederkassel to Stamboliyski | 1,022.13 mi (1,644.96 km) |
| Niederkassel to Stara Zagora | 1,051.75 mi (1,692.63 km) |
| Niederkassel to Svilengrad | 1,103.08 mi (1,775.24 km) |
| Niederkassel to Svishtov | 989.25 mi (1,592.05 km) |
| Niederkassel to Targovishte | 1,054.05 mi (1,696.33 km) |
| Niederkassel to Teteven | 976.41 mi (1,571.37 km) |
| Niederkassel to Troyan | 995.40 mi (1,601.94 km) |
| Niederkassel to Tryavna | 1,026.88 mi (1,652.61 km) |
| Niederkassel to Tutrakan | 1,023.46 mi (1,647.10 km) |
| Niederkassel to Varna | 1,109.70 mi (1,785.89 km) |
