Oldest known icon of Christ the Saviour (Pantokrator), 6th-c. encaustic on panel -- from Saint Catherine's Monastery, Mount Sinai (one of oldest working Christian monasteries -- Egeria provides oldest account of monastic life here during her pilgrimage, in Latin, 381-384 AD). The monastery was ordered built by Emperor Justinian I (527-65 AD). The library has 2nd largest collection of early codices & manuscripts & best collection of early icons in the world.