Perched above an artificial lake some 30km northwest of Urbino by road, SASSOCORVARO is dominated by one of Francesco di Giorgio Martini’s most ambitious fortresses. Built on the orders of Federico da Montefeltro for one of his condottieri (mercenary soldiers), Ottaviano degli Ubaldini, it was, like San Leo, designed to withstand the onslaught of cannon. Unfortunately, the site lacked San Leo’s natural advantages and Francesco was forced to seek a strictly architectural solution, doing away with straight walls and building a grim fortress bulging with hourglass towers. After the functional exterior, the inside comes as something of a surprise, with an elegant Renaissance courtyard and an intimate and frescoed theatre. It’s a tribute to the strength of Francesco’s architecture that the fortress was selected as a safe house for some of Italy’s greatest works of art during World War II, including Piero della Francesca’s Flagellation and Giorgione’s La Tempesta, reproductions of which are on show. There’s also a museum of traditional rural life, with displays of traditional weaving, wine-making equipment and a mock-up of an old kitchen.