The Ten Books on Architecture – Vitruvius

"Firmness, Commodity, and Delight."

Written around 15 BC, this is the only surviving treatise on architecture from classical antiquity. Vitruvius covers everything from city planning and materials to temple design and hydraulics. He famously asserts that a building must exhibit three qualities: firmitas (strength), utilitas (utility), and venustas (beauty).

Vitruvius's work was rediscovered in the Renaissance and became the bible for architects like Palladio and Michelangelo. It codified the classical orders and the principles of proportion (leading to Da Vinci's Vitruvian Man), shaping the built environment of the Western world for centuries.