The mother of Emperor Constantine I the Great, St. Helena, had a chapel built on the site where, according to tradition, Moses spoke to God in the biblical episode of the "burning bush". Later Emperor Justinian I had a monastery built on the site, next to the chapel mentioned above. The monastery was built between 527 and 565. The bush that remains is supposed to be the original bush, making the monastery a sacred place for the three great monotheistic religions: Judaism, Christianity and Islam.
Although its real name is the Monastery of the Transfiguration, it is also known as the Monastery of St Catherine, named after St Catherine of Alexandria, a Christian martyr who was sentenced to die on the torture wheel. Tradition has it that the wheel broke and that she was finally beheaded. Her body was taken by angels to Mount Sinai and the monks of the monastery found her remains around 800 in a mountain grotto, from which time the monastery guarded her relics and became an important center of pilgrimage.
The monastery has a document, the Ashtiname of Muhammad, that supposedly is in the handwriting of the prophet Muhammad himself, giving his protection to the monastery after it granted him refuge. Thanks to this special document and a Fatimid mosque built within its walls, the monastery survived the Muslim domination of the region. The mosque is now closed and has never been used because, by mistake, it does not face Mecca.
The anchorites of Sinai were eliminated during the 7th century and only the monastery survived thanks in part to the fortifications that protected it. The monastery still retains its defensive walls. Until the 20th century, access to the interior of the enclosure was by means of a raised gate in the outer wall. The monastery became an even more important center of pilgrimage between 1099 and 1270 in the Crusades era. The monastery was supported by dependencies in Egypt, Palestine, Syria, Crete, Cyprus and Constantinople.