Samuil Fortress is the name of a medieval fortress located between the Belasitsa and Ograzhden mountains in the Klyuchka gorge.
It is located on the low hill Kufalnitsa, located on the right bank of the river Strumeshnitsa, 5 km north of the village Klyuch. [1] It was probably built in the period 1009 – 1013 during the reign of King Samuel and is part of a large fortification system.
source: en.wikipedia.org