Daniele Barbaro’s treatise on perspective is one of the most authoritative technical-scientific sources of the sixteenth century. Although largely based on the unpublished work of Piero della Francesca, the treatise had the precise and original purpose of filling a gap in the Vitruvian text about the contents of the so-called ‘scaenographia’, a discipline based on optical geometry of which Vitruvius provided only meagre and sibylline words. The subdivision of the treatise, examined here into the individual parts that constitute it, follows a clearly Vitruvian structure, with the first three parts dedicated to ichnographia (perspective drawing of plans), orthographaia (perspective drawing of solid bodies) and scaenographia (perspective drawing of the buildings and their ornaments), and with two other parts specifically dedicated to the measurements of the human body and to the drawing of the planisphere, themes treated by Vitruvius respectively in the third and ninth books of De architectura. In this sense, La pratica della perspettiva, published in 1568, should be considered as an integral text of the most authoritative commentary on Vitruvius’ I Dieci libri dell’architettura, published in 1556 and 1567.