In 1458 Aeneas Sylvius Piccolomini, born in Corsignano in 1405, was elected Pope. He gave himself the name of Pius II and decided to rename his birthplace Pienza and to transform it into a model city of the Renaissance. The architect Bernardo Rossellino received the commission. Work on the cathedral began in 1459. The location directly on the slope of the town hill led to a lowering of the ground. This can be clearly seen from the crack that runs right through the floor tiles and the wall (in the panorama covered by a column). In order to detect changes in the crack, the wall was equipped with several measuring instruments. Currently (2020) extensive restoration work is underway. UNESCO World Heritage since 1996