Piranesi was born in Mogliano Veneto, near Treviso, then part of the Republic of Venice. His father was a stonemason. His brother Andrea introduced him to Latin and the ancient civilization, and later he was apprenticed under his uncle, Matteo Lucchesi, who was a leading architect in Magistrato delle Acque, the state organization responsible for engineering and restoring historical buildings.
From 1740 he had an opportunity to work in Rome as a draughtsman for Marco Foscarini, the Venetian ambassador of the new Pope Benedict XIV. He resided in the Palazzo Venezia and studied under Giuseppe Vasi, who introduced him to the art of etching and engraving of the city and its monuments. Giuseppe Vasi found Piranesi's talent was beyond engraving. According to Legrand, Vasi told Piranesi that "you are too much of a painter, my friend, to be an engraver."
After his studies with Vasi, he collaborated with pupils of the French Academy in Rome to produce a series of vedute (views) of the city; his first work was Prima parte di Architettura e Prospettive (1743), followed in 1745 by Varie Vedute di Roma Antica e Moderna.