It's also the second richest library on Earth (after the Vatican Library), due to the number and value of its books
Considered one of the oldest Christian monasteries in the world still in operation, the Monastery of Saint Catherine in Sinai is home to more than two millenia of history — and more than that of legend. Tradition claims, for example, that the main altar of the monastery is built on the spot where the Burning Bush first addressed Moses. But the monastery, declared a world heritage site by UNESCO, also holds other seats of honor. For example, it accommodates the oldest continuously operating active library in the world.
From the day it was founded in the sixth century (between 548 and 565), the library of St. Catherine at Mount Sinai has never closed its doors. Built during the reign of Justinian I, the building was originally sponsored by the mother of Constantine the Great, Empress Helena. Its walls are still home to ancient Roman scrolls dated back in the days when the monastery itself was founded, which makes Saint Catherine’s the second largest collection of codices and manuscripts in the world, right after the Vatican Library in Rome. In fact, from this monastery comes the famous Codex Sinaiticus, the biblical text dated to the year 345.
The collection of the monastery, as explained by Dattatreya Mandal for Realm of History, includes a copy of the Gospels from the 5th century, a copy of the “lives of the holy women” of 779 and a copy of the Apology of Aristides, probably one of the few surviving, as the original Greek version still remains lost, and number of Arabic manuscripts among which a copy of the “Ashtiname Muhammad” can be found. In this text the Muslim prophet claims to offer protection to the monastery, grants tax exemptions to the Christian monks of the monastery and also exempts them from military service during the years the area was under Islamic rule.
Currently, the library at UCLA is about to start a project to digitize approximately 1,100 unique Syriac and Arabic manuscripts preserved at the monastery, dating from the 4th to the 17th centuries.