Bonaccorso Ghiberti (1451-1516), grandchild of the famous artist Lorenzo, had inherited his grandfather’s workshop, continuing to run it as a foundry. His Zibaldone is a notebook dedicated to architecture, engineering, metallurgy, mathematics and practical geometry. It contains ideas from Vitruvius’ De architectura and Valturio’s De re militari, as well as various machines designed by Filippo Brunelleschi for the construction of the dome of Santa Maria del Fiore. It is possible that it helped young Leonardo to discover Brunelleschi’s machines and other contemporary technical devices (for example, projects for self-propelled siege bridges, cf. Codex Atlanticus, f. 1074r).