Karnak's Great Hypostyle Hall is the building in which stone pushes the post-and-lintel principle to its limit in order to roof an enclosed interior. The problem is simple but its solution costly: stone is strong in compression but weak in bending; the span a stone lintel can cross without breaking is very short. Rather than overcome this constraint, the Egyptian builders accept it and crowd the columns together — the price of keeping spans short is a forest of columns.

The result is 134 columns filling an area of some 5,000 m². The central two rows are markedly taller than those at the sides; this difference in height is not structural but luminous. Stone-grilled clerestory windows are set into the vertical gap between the tall central nave and the lower side aisles; light enters from above, sliding in sideways. The space thus becomes closed from outside and dim, vertical and forest-like within — capitals imitating bundles of papyrus crown the metaphor of the forest.

From here the hypostyle ('borne by columns') hall becomes one of the basic interior typologies of Mediterranean and Near Eastern architecture; it is an ancestor of a lineage running from the Persian Apadana to the many-columned (hypostyle) plan of early mosques. Karnak is the monument to turning stone's span limit into a creative spatial experience — a forest of columns full of light, scale, and rhythm.