Hypostyle Halls

Most Ancient Egyptian temples possessed a hypostyle hall. Hypostyle is an Ancient Greek term denoting a building having rows of columns supporting its roof. As befitting a "divine mansion," Egyptian temples were imposing structures often built of stone on a large scale. Some even had two or more hypostyles. Rather than one or two modest wooden pillars, temple hypostyles usually boasted at least four stone columns. Usually, temple columns mimicked the appearance of papyrus reed stalks, their capitals resembling either closed floral buds or massive bell-shaped papyrus flowers in full bloom. Larger hypostyles might be populated with a dozen or more columns. 
Columns along the central axis were built taller than the rest to support a higher roof in the central nave. The difference between the height of the nave and the side aisles resulted in a design similar to ancient Roman basilicas and medieval Gothic cathedrals and, like these structures, allowed their builders to insert windows in an attic space called a clerestory.

 

clerestory diagram

 

Diagram showing the layout of the Hypostyle Hall, with its columns, architraves and clerestory.