Isolated and protected by the surrounding majestic mountains .Early Christian hermits, searching seclusion from worldly affairs, were living around the holy mountain since the early times of Christendom. 
After her visit to the impressive site of the Burning Bush Empress Helena, the mother of Constantine the Great, decided in 330 AD to let a chapel be build at the site; and dedicated it to the Virgin Mary. 
Many travelogues from early pilgrims talked about the massacres among the monks. Finally in 527 AD Emperor Justinian ordered the construction of a fortress. Above the heavy wooden entrance wooden frames carry the names of Justinian, his wife Theodora and the architect’s Stephanos.
St. Catherine is among the oldest Christian monasteries, and the smallest diocese in the world. The Monks today are Greek Orthodox and of different nationalities.

The monastery at the base of Jebel Musa preserves the tradition from the Byzantine period of identifying this as Mount Sinai. Named after a saint who was martyred in Egypt in 307 A.D., the monastery has a library with the second finest collection of manuscripts in the world (after the Vatican), including 3,500 manuscripts and 2,000 scrolls. Most of these are in Greek and were copied by the monks of this monastery. In 1844, the German scholar Friedrich von Tischendorf discovered Codex Sinaiticus here, one of the earliest copies of the Bible (4th century A.D.).

The Chapel of the Burning Bush

were the first time GOD talk to MOSES. is the sacred part of the monastery. Once it contained the Burning Bush, which is replaced outside of the chapel and fenced behind a stone wall. Every Saturday the monks hold their liturgy in the chapel.

Not only survived the diocese in an Islamic environment; it could also preserve the world's richest collection of icons. In 730 Emperor Leo banned and ordered the destruction of all images of worship, since it was offending against the second of the Ten Commandments. The iconoclasm resulted in vandalism destroying countless icons. Many Christians died in the controversy. In 787 the Council of Nicea declared that Jesus possessed Two Natures, the divine (and untouchable) and the human, which was legal to depict in artwork.

More than 2000 icons represent a mirror of Christian history, telling from the separation of the Latin and

Eastern churches

It is a spectacular natural setting for priceless works of art, including Arab mosaics, Greek

and Russian icons, Western oil paintings, paintings on wax, fine sacerdotal ornaments,

marbles, enamels, chalices, reliquaries, including one donated by Czar Alexander II in the

19th century, and another by Empress Catherine of Russia in the 17th century. But of

 perhaps even greater significance is that it is one of the  largest and most important

collection of illuminated manuscripts in the world (The Vatican has the largest). The

collection consists of some 4,500 volumes in Greek, Coptic, Arabic, Armenian, Hebrew, Slavic, Syriac, Georgian and ot herlanguages