Fortress with fuor-side corner towers, built for Pope Julius III, because of the continuing unrest that followed in the first half of the sixteenth century. Work began in 1554 on a design by Jacopo Barozzi da Vignola, who conceived the building halfway between fortress and palace of Government. The severity of the exterior contrasts with the elegance inside. The front door leads in former Chancellery Civil and Criminal; the courtyard in the center of the building leads to a range of environments: the courtroom, stationery, prisons, stables and the torture chamber, which through an underground passage you can get outside the city walls. Source of the courtyard there is a stipendiary figure, identified as Vespasian Polla, mother of Emperor Vespasian. Today, the Castellina is home to a rich Diocesan Museum that also includes works by artists such as Jacopo della Quercia, and Luca della Robbia.