Vitruvius. The Ten Books on Architecture. Translated by Morris Hicky Morgan.

Elibron Classics Series. This is a digitized replica of 1914 edition by Harvard University Press, Cambridge. This is an Illustrated edition.
This is the only full treatise on architecture and its related arts to survive from classical antiquity, the Architecture libri decem (Ten Books on Architecture) is the single most important work of architectural history in the Western world, having shaped architecture and the image of the architect from the Renaissance to the present.