| Castle Rock to Popovo | 5,956.62 mi (9,586.25 km) |
| Castle Rock to Provadia | 6,000.93 mi (9,657.56 km) |
| Castle Rock to Radnevo | 6,006.56 mi (9,666.63 km) |
| Castle Rock to Radomir | 5,901.52 mi (9,497.58 km) |
| Castle Rock to Rakitovo | 5,967.83 mi (9,604.29 km) |
| Castle Rock to Rakovski | 5,978.00 mi (9,620.67 km) |
| Castle Rock to Razgrad | 5,954.61 mi (9,583.02 km) |
| Castle Rock to Razlog | 5,954.15 mi (9,582.28 km) |
| Castle Rock to Ruse | 5,921.93 mi (9,530.42 km) |
| Castle Rock to Samokov | 5,932.01 mi (9,546.65 km) |
| Castle Rock to Sandanski | 5,965.65 mi (9,600.78 km) |
| Castle Rock to Sevlievo | 5,941.50 mi (9,561.93 km) |
| Castle Rock to Shumen | 5,980.80 mi (9,625.17 km) |
| Castle Rock to Silistra | 5,943.13 mi (9,564.54 km) |
| Castle Rock to Sliven | 5,996.98 mi (9,651.21 km) |
