With the rediscovery of Mariano Taccola’s technical manuscripts, a primary source has been found for drawings and texts in treatises and sketchbooks of Francesco di Giorgio Martini. Taccola first conceived a new subject in Renaissance literature: rational descriptions and illustrations of utilitarian structures built by master masons, carpenters, millwrights, and artisans in the service of military lords. Taccola’s complex and fascinating manuscript is being published fully in facsimile. It was a gift to Johann Albrecht Widmannstetter who studied law (1533-1542) in Siena, probably at the Studio or University where Taccola had been secretary while writing in the building arts. The volume that Taccola entitled “Liber primus leonis” and “Liber secundis draconis” was modified into a “Notebook” when he, in 1435-1438, added many small sketches around each main drawing existing on a folio, and added quires of paper after Book II for additional and later drawings. This edition includes, in the editors’ introduction, a short biography of Mariano Taccola, a history of his “Notebook”, a description of its sections, an account of Taccola’s contribution to the history of thechnology, and a study of his influencce. Each of Taccola’s several hundred drawings is identified, his Latin texts and notes are all transcribed an then translated into English. In one Appendix, the editors illustrate and interpret eight drawings identified as copies of Taccola’s originals lost from his “Notebook”, and a second Appendix concerns the desings of mills, pile-drivers, and water-supply devices of a Machine Complex that other engineers developed from prototypes in Taccola’s “Notebook”.