The Renaissance ideal piazza, built from scratch by Bernardo Rossellino between 1459 and 1462. The cathedral closes one side; the Palazzo Piccolomini and the Palazzo Borgia face each other across the open paving; the town hall sits in the remaining corner. Every line was drawn on a fresh plan: the proportions, the inclination of the side palaces, the trapezoidal paving — all are part of a single composition.
It is one of the smallest squares of its kind in Italy and one of the most copied. Sit on the cathedral steps for half an hour and watch the light move across the travertine, then walk through to the loggia behind the Palazzo Piccolomini for the view that completed Pius II's vision.