The cardinal therefore obtained a bull from Pope Paul II., permitting him to recall his original donation, and in a letter dated from the baths of Viterbo, May 13th, 1468, he made over his library to the republic. The principal treasures of the collection, including splendid Byzantine book-covers, the priceless codices of Homer, the Grimani Breviary, an early Dante, &c., are exhibited under cases in the Sala Bessarione in the Zecca or mint where the library has been installed.
On the decoration of the Sala del Cambio, or old exchange, Perugino put forth the full force of his genius.
In the baths were found a number of works of art, now in the Vatican, notably the mosaic pavement of the Sala della Rotonda, and the celebrated head of Zeus and the head of Claudius in the same room.
Another hall, the Sala di Balia, has frescoes by Spinello Aretino (1408) with scenes from the life of Pope Alexander III., while yet another has been painted by local artists with episodes in recent Italian history.
Como suffered considerably from the early barbarian invasions, many of the inhabitants taking refuge on the Isola Comacina off Sala, but recovered in Lombard times.