COVE

Created by Da Vinci while working for Cesare Borgia, but likely meant for the Florentine government at the time, this map displays the different waterways in the valley, which could be used for making a dam.

This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1923. Courtesy of Wikimedia Commons. 

Source: “A Map of the Valdichiana.” Royal Collection Trust, www.rct.uk/collection/912278/a-map-of-the-valdichiana.