This comes from the Byzantines.net website. I would like to do a series on the order and decoration of Byzantine Churches. I think their strong catechetical focus with regards sacred imagery is fascinating. - SRT.
The interior of a Byzantine Catholic Church is described as "heaven on earth" - the place where God dwells and where man can "lay aside all earthly cares." Between the altar and the congregation there is the iconostasis, which establishes the unity between God and man; where the material and sensory worlds meet.
The screen symbolically divides the heavenly world (the altar area) from the human world (the main body of the church), and unites these worlds into one whole. Standing on the boundary line between the heavenly and human worlds are the images (icons) of Christ, the Mother of God, and the saints, through whom salvation is accomplished.
The iconostasis is composed of three doors and up to four rows of icons. Most churches today build lower screens of only two rows of icons.
The icon screen has a double door in the middle. These are called the Royal or Holy Doors because only the bishop or priest can pass through them. These doors are usually decorated with the Annunciation (Angel Gabriel telling Mary she is to be the Mother of God), and the four Evangelists (those who announced the good news of salvation to the entire world). These doors represent the gates of heaven.
On either side of the Royal Doors are the Deacon or Servers Doors. These are single doors used by the deacon or servers who assist the priest during the liturgy. On these doors can be found icons of a deacon saint, usually Saint Stephen the Protomartyr, or an angel, usually St. Michael.
To the immediate right of the Royal Doors is the icon of Christ the Teacher. To the left, is the icon of the Mother of God. On either side of the Deacons' Doors is the patron saint of the church (right side) and St. Nicholas, patron saint of the Byzantine Catholic Church (left side).
The twelve major feast days of the Byzantine liturgical year can be found over the doors on the second row of icons. These represent the main events to salvation. In the center of this row, above the Royal Doors, is the icon of the Mystical Supper. Since this event is reenacted during every liturgy, it is a focal point on the iconostasis.
If the iconostasis contains more than two rows of icons, the central figure of the upper sections is that of Christ in His glory, the Pantocrator, sitting on a throne as the King of the Universe. On both sides of Christ, in the third and fourth rows, are the Apostles, Prophets and Patriarchs of the Old Testament. It is topped with a Crucifixion, with the Mother of God and St. John the Evangelist standing beneath the cross. It was through the Crucifixion and the Resurrection that salvation was accomplished and the gates of heaven opened.