During his apprenticeship in the Florentine building yards, Leonardo has the chance to observe many cranes, among which those designed by Brunelleschi. He draws them on many pages of his manuscripts. These models are designed to be used in stone pits and canal digs. Rotating cranes work on heights and allow rapid racking of materials. In the double-arm version, the movement is facilitated by a counterweight. The cranes can also be pulled on rollers for short distances.