Designs for the Palazzo dei Priori date back as far as the 1270s. A first part consisting of 3 triple-windows towards the square and 10 along Corso Vannucci was built between 1293 and 1297. A first extension of the building took place between 1333 and 1337, with the addition of two more triple-windows towards the piazza, as well as the stairs and balcony. After 1353 a second extension was added on the Corso, with six triple-windows, the large doorway and the originally fortified tower that surmounts the access to Via dei Priori. A third extension was carried out between 1429 and 1443 with the addition of three more triple-windows and the section containing the Collegio del Cambio. The asymmetrical and irregular facade of the building is the result of the various stages in which it was built. The perimeter of the roof was originally crenellated, symbolising the power of the free city. When Perugia fell to the papal armies the crenellations were demolished in 1610. The upper part of the tower had been destroyed in 1569. The crenellations we see on the roof did not reappear until 1860, with the unification of Italy. The stairs in Piazza IV Novembre lead to a Gothic portal surmounted by the city's symbols, the griffin and lion. The portal leads into the Sala dei Notari, formerly the Town Council Hall, which was allocated to the notaries guild in 1582. Their former headquarters, the Palazzetto dei Notari, opposite Palazzo dei Priori in Corso Vannucci, had had to be partially demolished to enlarge the left side of Via Calderini. The facade that gives onto Corso Vannucci has another fine Gothic portal, dated 1346. The three statues in the lunette represent St. Laurentius, St. Ludevic of Toulouse and St. Herculanus, the patron saints of Perugia. The lateral pillars rest on crouching lions and are surmounted by two griffins clasping calves in their claws. This is a symbolical allusion to the guild of butchers, one of the main funders of the construction. The portal leads to the third floor, that houses the Galleria Nazionale dell Umbria.