During the period of Ottoman rule in Bulgaria, many valuable books and manuscripts from the Second Bulgarian State were stored in churches in Tarnovo.
According to legend, following the conquest of Tarnovo, the books and manuscripts were hidden in the Patriarchal Church of St. Peter and Paul, along with concealed royal letters and contracts, many of them inscribed and decorated with miniatures.
Later a Hellenic bishop found the artifacts and ordered that they be burned, which supposedly took days to accomplish.
[citation needed] The complex has housed a museum and a library, with construction beginning in the 1940s.
In 1971, the library was awarded the Cyril and Methodius Order I for its 50th anniversary.