I Quattro Libri di Architettura (The Four Books of Architecture).

First published in Italian in 1570, Palladio’s treatise popularized classical decorative details, becoming what is probably the most influential architectural book ever printed. Incorporating many of his own designs to illustrate the principles of classical Roman architecture, Palladio strongly influenced 18th-century architecture in the British Isles, Italy and America. While Palladio’s work was the most common architectural book owned by designers and builders, it was difficult to obtain in America. Thomas Jefferson commented in 1804 that “there never was a Palladio here [in Washington] even in private hands till I brought one… the chance of getting one in America is slender.”