The Sienese artist-engineer Mariano Taccola left behind five books of annotated drawings, presently in the collections of the state libraries of Florence and Munich. Taccola was well known in Siena, and his drawings were studied and copied by artists of the period, probably serving as models for Leonardo da Vinci's notebooks. However, his work has received little attention from scholars and students in recent times. The author, a sculptor, has long been interested in Taccola's drawings for his studio projects. Although Taccola lacked the fine drawing hand displayed by many of his contemporaries, his inventive work may appeal especially to viewers today. Based on examination of the original drawings, the author discusses the qualities that make Taccola's drawings unique and considers what Taccola's intentions may have been in making them.