The Diocese of Pienza (Latin: Dioecesis Pientinus) was a Roman Catholic diocese located in the town of Pienza in the province of Siena, in the Val d'Orcia in Tuscany between the towns of Montepulciano (fifteen km distant) and Montalcino. Until 1462, the town was known as Corsignano. It took the name Pienza from its most famous native son, Pope Pius II (Aeneas Silvius Piccolomini), who elevated the town to the status of a city (civitas), and established the new diocese. The diocese existed as an independent entity from 1462 to 1772, directly subject to the Holy See (Papacy).