Cartography

The irregularities in the rectilinear street plan of Imola testify to the accuracy of the map, which may still be used to find one’s way around today.

After leaving Borgia’s service Leonardo returned to Florence, where he continued to make maps. Some were presumably commissioned by the Florentine government, such as surveys of the Valdichiana in southern Tuscany.

Others record Leonardo’s proposal to construct a canal to bypass the river Arno. The Arno is not navigable as far as Florence because of rapids 15 km west of the city and around 1503-4 Leonardo was promoting the building of a canal. There is no evidence that his plan was ever seriously considered by the Florentine government.

During the summer of 1504 Leonardo surveyed further stretches of the Arno east and west of Florence. From these surveys Leonardo constructed careful maps of both areas. The notes and colours in many of these maps demonstrate that the maps were intended to be seen by others. They were likely commissioned by the city government.

Leonardo continued to produce maps throughout his life. In 1514 Pope Leo X charged his brother Giuliano de’ Medici – Leonardo’s patron in Rome- with draining the Pontine marshes. Attempts had been made to drain these malarial marshes since Roman times.

For this project Leonardo produced a map of the Pontine marshes, although it is likely that this was based on an earlier map, and that Leonardo may not have visited the area himself.