In the Renaissance, people dreamed of a perfect city, in which men could live in harmony with themselves and the nature. Pienza is a city close to this utopian model. We are in Val d'Orcia, where Pope Pio II ordered the construction of a project for an ideal city to be realised by Leon Battista Alberti: the town's symbols are the Gothic style Cathedral and Piccolomini Palace. The biography of the enlightened Pope is pictorially narrated in Siena, at the Piccolomini Palace library, located inside the Cathedral.