According to Bulgarian archaeological and historical research from 2004, it is the oldest active monastery in Europe. An expedition led by doctor and academician Rosen Milev was carried out on 18 January 2004, affirming that the monastery was founded by Athanasius of Alexandria in 344 while returning from the Council of Sardica in present-day Sofia. On the way back he stopped and slept in a Roman fortress, the remains of which are located close to today's monastery, deciding to found a monastery due to the strong influence of the Arians (see Ulfilas), whom he considered heretical, on the Goths living in the region of Beroe (modern Stara Zagora). After his death in 373, the monastery was named after him. This is regarded to be proven by the passional of Saint Athanasius and the annals of th