All of the architecture that surrounds the most important piazza of Pienza was designed by Bernardo Rossellino between 1459 and 1462, such as the Cathedral of the Assumption, which stands on the site of the old parish church of Santa Maria, with a facade in Travertine marble and a roof with two slopes that recall the Gothic Franciscan style. The cathedral is home to many precious paintings, including the Assumption by Vecchietta and the Madonna and Child Enthroned with Saints by Matteo di Giovanni. The Piccolomini crest is carved into the gable of the facade, encircled by a garland of fruit.
On the left we find Palazzo Borgia, which Pius donated to the Cardinal Rodrigo Borgia, future Pope Alexander VI. Today it is the Diocesan Museum.
Also looking out onto the piazza is the town hall, with its short, squat clock tower. Inside there is a precious fresco from the 15th-century Sienese school, depicting the Madonna and Child and the nobles of Pienza. Palazzo degli Ammannati, meanwhile, can be found where the piazza meets the Corso Rossellino.