These volcanic hills stand 20 kilometres southeast of Rome. The dominant peak, Monte Cavo, has two small calderas, both containing lakes, one of which is called Lake Nemi. The summit was often the site for celebrations by Roman generals after victories during the era when it was illegal for them to do so in Rome.
By the early 1500s, Cesare Borgia had established a weapons factory in the area, manufacturing chariot-mounted machine guns designed by Leonardo da Vinci. In 1502, the Assassin Ezio Auditore da Firenze broke into the factory, burning the machine's plans and destroying the two prototype machines.