'In February 1459, the Humanist Pope Pius II (Enea Silvio Piccolomini) paid a visit to Corsignano, his native village, and decided to change it into an ideal city to be called Pienza, the city of Pius. Within three years, the Piazza Pio II would be enclosed within a group of buildings that included the cathedral, a papal palace, a city hall, and a bishop's palace. Leon Battista Alberti, one of the most famous architects of the period, took part in the visit and gave advice to the Pope, but the task of designing and constructing the ideal city was given to Bernardo Rosselino (1409-1464). Rosselino was a distinguished architect in his own right and was also the architectural executant for Alberti on the Palazzo Rucellai in Florence (1447-1451). The pope, who was keenly interested in architecture, engaged with Rosselino in a process of intense collaboration.
In the center of the village, at the end of a main street that measures just under 1,000 feet in length, Rosselino created a town square such that the approaches from the intersecting side streets would be visually attractive. Rosselino treated the square, or piazza , 90 by 80 feet, as if it were an interior room with walls created by the façades of the cathedral and the three surrounding buildings. For Rosselino, town design was simply an extension of architecture. He designed the piazza/room as a strict exercise in perspective, organizing the pavement as a horizontal grid and the building façades as vertical grids, like those that would be used in constructing a perspective drawing of the square. The pattern of the rectangles implied by the grid identify the mathematical rules used in creating the proportions for all aspects of the piazza. This sort of construction conformed to Alberti's theories.
Rosselino treated the façade of the cathedral like a Roman triumphal arch . The plan of the church, like that of the piazza, is square, so that volumes of church and square are nearly comparable, the piazza being an "open room" and the cathedral an enclosed room--a "covered square." Pius, who had developed an interest in Late Gothic Austrian church design when he was apostolic secretary and ambassador, chose to build Pienza cathedral as a German "Hallenkirche," a church with nave and side aisles of the same height.
To the right of the cathedral, the Pope's Palace, called the Palazzo Piccolomini, was designed by Alberti and built by Rosselino. It closely resembles the Palazzo Rucellai, which the same pair built in Florence. The façade is built of mellow ocher stone with all details organized by the dominant rectangular grid. Windows in the upper stories are bipartite, that is, divided in two by a central column and framed by a thick, round arch at the top and two pilasters to the sides. Two strong horizontal stringcourses resembling classical entablatures divide the three stories and the palace is topped by a powerful cornice . The module of the bifurcated window between pilasters is repeated on the walls, giving a visual density to the palace block. Like Florentine palaces, there is a square interior courtyard, from which a gallery leads to a planted terrace that overlooks the immensity of the surrounding landscape. Analogous to the piazza-church pairing, the area of the terrace-garden is equal to the ground plan of the palazzo, creating a similar case of open versus closed volumes. To carry the open/built comparison further, the piazza, the cathedral, the palazzo, and the terrace-garden are all comparable in size, and they oblige us to consider and to understand the way in which they were combined by Rosselino.
The Bishop's Palace and the town hall are simpler than the other two buildings and they follow Tuscan tradition. The façade of the town hall opens into a lovely Ionic gallery. Although the mixture of different architectural styles may be surprising, it actually reflects the flexibility of Renaissance design.
A closer look at the space of the piazza reveals that the walls of the Palazzo Piccolomini, the bishop's palace opposite, the town hall, and the cathedral are not perpendicular to each other. As at Michelangelo's much later Campidoglio in Rome, the buildings create a trapezoidal plan for the piazza, in effect reversing the normal perspective sense of parallel lines appearing to converge. The effect is to make the façade of the cathedral seem larger than the façade of the papal palace, which is in fact the larger of the two buildings.
One more element should be noted: the exterior landscape. Two openings between the palace and the cathedral, and between the town hall and the cathedral, reveal the countryside with a view of distant mountains, a view of Mount Amiata covered with snow in the winter. Like the terrace-garden of Palazzo Piccolomini, the cathedral choir sits on the very edge of the village's platform above the valley. The Piazza Pio II demonstrates to how great a degree the new element of Renaissance design, the landscape, influenced the planning of the city. Pius II, a highly educated man who was fond of art and deeply involved in the poetry of the natural environment, was so fascinated by the forest and the open-air landscape that he took Catholic cardinals to the mountain facing Pienza and gave audiences to ambassadors by a spring where water cascaded into a lake.'
Furnari, Michele. Formal Design in Renaissance Architecture from Brunelleschi to Palladio. New York: Rizzoli, 1995.
Mack, C. R. Pienza: The Creation of a Renaissance City. Ithaca, NY: Cornell University Press, 1987.
Pienza, View of the well, Pozzo dei Cani
in the Piazzo Pio II
Pieve di Corsignano