The Holy Doors (also called the Beautiful Gate or the Royal Doors, though the latter more properly refers to the imperial entrance into the nave) are the central doors of the iconostasis, directly in front of the altar in an Orthodox church.
On the Doors there is usually a diptych of the Annunciation. Sometimes they may also have the icons of the four evangelists. To the right of the Doors (facing the iconostasis from the nave there is always an icon of Christ, to the left is an icon of the Theotokos holding Christ, and directly above is the Last Supper icon.
The Doors are opened at different points during the Divine Liturgy and other liturgical services depending on local tradition. However, they are almost always opened during the Great and Little Entrances, the Gospel reading, and the distribution of the Eucharist.