The Rila Monastery is the largest Eastern Orthodox monastery in Bulgaria, located in the Rila Mountains south of Sofia. Founded in the 10th century, it is one of Bulgaria's most important cultural and historical sites. Bachkovo Monastery is another important monument located on the Chepelare River, known for combining Byzantine, Georgian and Bulgarian influences. Troyan Monastery, Bulgaria's third largest, is situated on the banks of the Cherni Osam river near Oreshak. The Boyana Church was built in three stages from the late 10th century to the mid-19th century, decorated with ceramic ornaments. St. Alexander Nevsky Cathedral in Sofia has a gold-pl