In modern cathedrals, the sanctuary (the area of a church occupied by the altar) is often protected by a few steps or a handrail. In ancient Byzantine worship, the sanctuary was separated from the nave by an iconostasis, a wall adorned with images and icons. In addition to this adornment, the wall also contained an important doorway that permitted clergy to enter and exit the sanctuary. The doors that separated the congregants from this holy space symbolically represented the gateway that separated man from God, through which only the faithful could pass. In this period, the annunciation of Mary is often used as a symbol of this passageway as she was the conduit that delivered salvation to humanity. These doors from St. Catherine's monastery capture the iconography used to communicate this belief.