The monumental Mole Vanvitelliana in the harbor of the Adriatic City of Ancona is the spectacular setting for a most original Leonardo exhibition. For the first time Leonardo's presence at Urbino and Pesaro as an architect and general engineer in the service of Cesare Borgia in 1502 is presented in a historical and cultural context that includes every aspect of Leonardos art, science and technology, and also his philosophical outlook. The rarely seen materials, presented here in a fully illustrated catalogue, are also discussed in detail by seven scholars of international repute coordinated by the editor.