The library of the monastery of St. John, one of the greatest of orthodoxy, created by Christodoulos with handwritten books which he managed to transfer from his personal collection in Asia Minor.
With the passage of centuries, it has been enriched either through donations (emperors, Patriarchs, individuals) to the monastery or through those who came here to live a monastic life. Thus it turned into a real treasure house of books, maps, images and sacred relics.
The immeasurable value of it lies in the fact that the shelves hold 855 manuscript codices, of which 292 are papyrus, while there are more than 13,000 documents relating to the history of the monastery and of the island. The most important "treasures" of the library included the "Purple" code, as it is the oldest code of the monastery dating back to the 6th century and contains passages from the Gospel of Mark.