| Niederkassel to Popovo | 1,035.80 mi (1,666.95 km) |
| Niederkassel to Provadia | 1,091.29 mi (1,756.26 km) |
| Niederkassel to Radnevo | 1,068.75 mi (1,719.99 km) |
| Niederkassel to Radomir | 942.96 mi (1,517.55 km) |
| Niederkassel to Rakitovo | 1,012.08 mi (1,628.78 km) |
| Niederkassel to Rakovski | 1,031.62 mi (1,660.23 km) |
| Niederkassel to Razgrad | 1,039.80 mi (1,673.40 km) |
| Niederkassel to Razlog | 993.81 mi (1,599.39 km) |
| Niederkassel to Ruse | 1,005.28 mi (1,617.84 km) |
| Niederkassel to Samokov | 975.63 mi (1,570.12 km) |
| Niederkassel to Sandanski | 1,002.32 mi (1,613.07 km) |
| Niederkassel to Sevlievo | 1,004.76 mi (1,617.01 km) |
| Niederkassel to Shumen | 1,066.87 mi (1,716.96 km) |
| Niederkassel to Silistra | 1,047.47 mi (1,685.73 km) |
| Niederkassel to Sliven | 1,067.84 mi (1,718.52 km) |
