The fortresses designed by Francesco di Giorgio Martini characterize the landscape of the Montefeltro area, from better-known San Leo and Mondavio down to small and unknown wonders such as Sassocorvaro fortress (its plan resembles a tortoise), Cagli, Fossombrone, Sant’Agata Feltria, Montecerignone and Frontone. He was also the creator of the twin-turretted facade of the Ducal Palace in Urbino (the famous Torricini) and the Rampa leading to the Palace from Borgo Mercatale.