The Hagia Sophia (537 CE, Constantinople) is the quintessential Byzantine masterpiece, not Romanesque. Key distinctions:
| Feature | Hagia Sophia (Byzantine) | Romanesque (10th–12th c. Western Europe) |
|---|---|---|
| Dome | Massive central dome on pendentives | Rare; usually barrel/groin vaults |
| Plan | Centralized (near-square) | Longitudinal (basilica/cruciform) |
| Light | 40 windows at dome base; mystical glow | Small clerestories; dimmer interiors |
| Structure | Pendentives transfer load to 4 piers | Thick walls, buttresses, compound piers |
| Ornament | Gold mosaics, marble revetment | Architectural sculpture, frescoes |
Later Ottoman additions (minarets, buttresses) and the building's sheer age (pre-dating Romanesque by 500 years) sometimes blur categories. But historically and structurally, it defines Byzantine architecture.