It is traditionally thought that the monastery was founded by the hermit St. John of Rila (Ivan Rilski), whose name it bears, during the rule of Tsar Peter I (927-968). The hermit actually lived in a cave not far from the monastery's location, while the complex was built by his students, who came to the mountains to receive their education.

source: Wikipedia

Le monastère de Rila fut fondé par Saint Ivan de Rila vers l'an 930. Initialement il se situait à 4km de son emplacement actuel, dans le lieu-dit Les Cellules Blanches (Bélité Kilii).

source: la-bulgarie.fr