basilica
In ancient Roman architecture a large oblong type building used as hall of justice and public meeting place. The roman basilica served as a model for early Christian churches.

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

three-aisled basilica
An oblong type of church internally divided into three aisles: the middle and the two side aisles. The middle aisle is often lighted by an elevated clerestory. In the Early Byzantine years this type of church had huge dimensions.