The old town of Pienza is the first application of the Renaissance Humanist concept of urban design, and as such occupies a key position in the development of the concept of the ‘ideal city’ that was to play a significant role in subsequent urban development in Italy. The application of this principle in Pienza, and in particular in the group of buildings around the central square, resulted in a masterpiece of human creative genius. The humanist Enea Silvio Piccolomini (1405-1464), elected Pope in 1458 as Pius II, was born at Corsignano, situated on a hill overlooking the Val d’Orcia, a few kilometers south-east of Siena. When he returned there after becoming Pope, he was struck by the extreme poverty of its inhabitants, which inspired him to equip his birthplace of new buildings, and make it his summer court. His vision derived largely by the philosopher of German origin Cardinal Nicolà Cusano. The link with the German Gothic tradition is indicated by the Cathedral of Pienza, which the pope wanted in the same style of the gothic Hallenkirchen in Germany. The walled village of Corsignano consisted of a main road between the two doors, flanked by small parallel and perpendicular streets and was respected this basic structure, even for siting of the main buildings around the main square. The Pius II project also required the construction of large houses for the cardinals and their retinue. Two structures with a social function, the hospital and the inn opposite the church of San Francesco, were also built on his orders. The center of Pienza is the Piazza Pio II. Its trapezoidal shape is emphasized by the broadside travertine herringbone flooring. On the south side of the square is the cathedral (built from 1459 to 1462). On the west side of the square is the Palazzo Piccolomini, built in 1463 on the site of old houses owned by the family. The Bishop’s Palace is located on the opposite side of the square. The old Praetorian Palace was purchased in 1463 by Cardinal Rodrigo Borgia, who added an extra floor and replaced the Gothic windows. The Town Hall (1462), on the north side of the square is in traditional Tuscan style, with a loggia open on the ground floor and a crenellated tower. Other important buildings in Pienza are the Gothic church of St. Francis and his convent; Palace Atrebatense (Gothic structure with Renaissance decoration); Palace Ammannati, in the Renaissance style and the Palace Gonzaga, one of the few buildings that retains its garden.