It is not known who Ambrogio's teacher was, but his early works indicate that he early received his main inspiration from the art of Duccio, his brother Pietro, and Giotto. Already his representations reveal a realistic individualism and an intense preoccupation with significant composition and form. These characteristics are most evident in the “Allegories” in the Palazzo Pubblico, the most important Sienese fresco decoration. In it Ambrogio is seen as an acute observer, an empirical explorer of linear and aerial perspective, a student of classical works of art, and a political and moral philosopher. His desire to depict spatial depth convincingly led him to an increasingly accurate rendering of space in his paintings and almost to one-point perspective in his last work, the “ Annunciation.” With his profound interest in perspective and in classical antiquity, Ambrogio anticipated the Renaissance. The art of the Lorenzettis was widely imitated in Siena during the third quarter of the 14th century, and many works by close followers are still commonly attributed to one or the other brother.