In 1517, Leonardo was asked to design a new palace in France, where he had moved shortly after the fall of Sforza in 1499. The palace that he designed was vast and extravagant, and it had several similarities to the ideal city that he had designed years before. The palace would sit alongside a river, which would allow for a small network of canals to be constructed. The designs included two large, square-shaped palaces and enough smaller buildings around them to make a small village. Unfortunately, in 1519, Leonardo da Vinci passed away, and though his designs were mostly complete, they were abandoned. Because of this, many of his plans for the palace were lost over time, and extensive research has been done to try to recover the missing pieces of his design.

Source and Photo Source: http://www.leonardo-da-vinci.net/romorantin-palace/