In 1515, Leonardo probably traveled to Bologna, to attend the peace talks between the Pope and the new king of France, Francis I. Upon attaining the throne, Francis I had conquered Milan, and the Medici family was eager to make him an ally. As a peace offering, Leonardo constructed a mechanical lion, symbolizing Florence: the lion was able to walk a few paces, and then a trapdoor in his chest opened up to reveal a fleur-de-lis, symbol of France. The new King was impressed.
Leonardo was probably not very happy in Rome. Although Giuliano de Medici held Leonardo in high esteem, it is not clear whether the pope or his court granted him much appreciation. After all, they seemingly believed the ridiculous claims of a mere engineering assistant, that Leonardo was interested in necromancy, or the conjuring of the recently dead. Moreover, the pope may have had greater interest in other artists in Rome at the time, such as Michelangelo.
This period, like those before it, again sees Leonardo at a remarkable level of productivity. He was a consultant in numerous architectural and hydraulic projects. By this time, he was about sixty years old, yet he was full of pranks and was ready to study things that he had never seriously approached before, such as the properties of mirrors.