AT THE FOOT OF JEBEL MUSA, the traditional site of Mt. Sinai, lies the monastery known as St. Catherine’s (its actual name is the Monastery of the Transfiguration), which was built around the year 500 A.D. A popular site for pilgrimage, it encloses a fourth-century chapel erected by Emperor Constantine’s mother, Helena, to mark the site where God spoke to Moses from the burning bush. The Codex Sinaiticus was brought here sometime thereafter and remained, forgotten by the outside world for hundreds of years, until the 19th century.