aisle
Τhe part of the naos of a church set off by the internal rows of piers or columns, namely by the structures supporting the roof.

atrium
1. Antiquity: The large, open space within a building, which is envelopped by colonnades.2. Βyzantium: The forecourt of a church in early Christian, Byzantine, and medieval arcitecture. It was usually surrounded by four porticoes (quadriporticus).

dome
A characteristic element of Byzantine architecture. The dome is a hemispherical vault on a circular wall (drum) usually pierced by windows. The domed church emerges in the Early Byzantine years and its various types gradually prevail, while they are expanded in the Balkans and in Russia.

gallery
The upper level of a house where the women resided. In ecclesiastical architecture it is the corridor above the aisles and narthex of a church, from where women attended the Liturgy. Originally (in the Byzantine period) the gallery, having a special entrance, was used exclusively by the emperor and the members of the royal family.

narthex
A portico or a rectangular entrance-hall, parallel with the west end of an early Christian basilica or church.