Santa Maria delle Carceri

Prato, begun 1485

Architect:  Giuliano da Sangallo




The Miracle

The Church of Santa Maria delle Carceri in Prato, near Florence, was built to enshrine a painting of the Madonna that was seen by a child to be crying tears.  The name, "Carceri," which means "prison" in Italian, reflects the painting's location on the outer wall of a prison.



It was decided that a church should be built to commemorate the miracle by preserving the painting in a shrine where individuals could pray in its presence.


Following a competition, the commission was awarded to a local architect, but Lorenzo the Magnificent intervened, and the contract was given to Giuliano da Sangallo.  Lorenzo had been especially impressed with Giuliano's design for the Villa Medici the year before.


Unfinished Outer Surface

The marble encrustation was only partially completed in the Renaissance.  More was added in the nineteenth century, but in the twentieth century, restorers decided to leave the unsheathed part as found.


A graphically manipulated image gives some idea of how it would have looked if it had been finished.





Centralized Plan

Like most other votive churches, Santa Maria delle Carceri did not need to accommodate a large congregation, and a centralized plan could be employed.


Santa Maria delle Carceri represents an early application of a centralized plan to a church rather than a chapel.  In this it follows Alberti's San Sebastiano in Mantua, which was the first.  Had it been completed, this distinction would have gone to Brunelleschi's Santa Maria degli Angeli.


Main Parts

Santa Maria delle Carceri has a Greek-cross plan.  Its crossing is spanned by a dome on pendentives, and its equilateral arms contain a vestibule at the main entrance, an altar chapel at the other end, and recesses on the sides.


In using simple forms and restrained decoration, Santa Maria delle Carceri embodies greater simplicity and symmetry than earlier centrally planned structures.



The proportions have been calculated to reflect whole-number ratios, especially 1:1, 1:2, and 1:4.


=Arm width to arm depth (2:1). The width of the arms is twice their depth.


=Arm width to building span (1:2). The width of the arms is half the span of the building.


=Arm depth to building span (1:4). The depth of the arms is one quarter the span of the building.


=Arm width to entablature height (1:1). The width of the arms equals their height at the top of the entablature, from which the ceiling vaults spring.


=Axial span to transverse span to height at dome base (1:1:1). If the corners were filled in to form a square plan and the height was made level with the roof just below the dome, the resulting shape would be cubical.


Conformity with Alberti's Recommendations

A number of features of Santa Maria delle Carceri's design conform with Alberti's recommendations on church design.






The design of Santa Maria delle Carceri has similarities to Brunelleschi's Old Sacristy of San Lorenzo and the Pazzi Chapel of Santa Croce as well as to Alberti's San Sebastiano.


Comparison with San Sebastiano

Santa Maria delle Carceri was similar to San Sebastiano in having a Greek-cross plan.


San Sebastiano differed from Santa Maria delle Carceri in having arms that terminate in apses instead of being straight.  Its original design, which was not followed after Alberti's death, also differs in having features that compromise its bi-axial symmetry such as the stairs and a vestibule at the entrance end.


Similarities to the Pazzi Chapel

Santa Maria delle Carceri has many similarities to the Pazzi Chapel including a three-tier organization and high-contrast materials like pietra serena trim against white walls.


=Upper tiers. On their exteriors, the upper tiers of both buildings have cylindrical colonnaded lanterns on top of conical roofs that rest on cylindrical oculi-pierced drums.  On their interiors, both have sectional domes with radiating ribs.


=Middle tiers. On their middle tiers, both structures consist of pendentives decorated with glazed terracotta tondi.


=Lower tiers. On their lower tiers, the walls of both interiors are ornamented by pilasters carrying an entablature.  Both also use pilasters at right angles to trim outside corners, which creates the appearance of embedded pillars.


Differences from the Pazzi Chapel

Despite these striking similarities between Santa Maria delle Carceri and the Pazzi Chapel, they differ in several ways.


=Plan. They differ in plan because the Pazzi Chapel's plan is not a Greek cross although its axial and lateral projections are balanced around a center.


=Dome support. They differ in dome support because the dome of Santa Maria delle Carceri rests on a drum, and that of the Pazzi Chapel rises directly from the pendentives.


=Corners. They differ in using pilasters on inside corners because at Santa Maria delle Carceri, whole pilasters are used on both faces, and at the Pazzi Chapel, fractional pilasters are used on one of the facings).






The ornamentation of Santa Maria delle Carceri is restrained and coordinated with architectural features.


Terracotta Tondi and Frieze

On the interior, the tondi and frieze were made of white-on-blue glazed terracotta by Andrea della Robbia, who had continued the business begun by his uncle, Luca della Robbia.  The frieze depicts draped garlands and fluttering ribbons attached to supportive devices.


Carved Architectural Trim

The figured capitals of the interior are each carved differently, and Giuliano is believed to have carved some, or perhaps, even all of them.


Winged symbols of the Four Evangelists have been adapted to occupy the corners of the capitals. Fleurs-de-lis, symbols of Prato, are located between the Evangelists and in the coats of arms in the frieze.





Encrustation of Polychrome Marble

The exterior of Santa Maria delle Carceri is faced with marble of contrasting colors.


Although it had been the principal surface treatment for late-medieval Tuscan churches, the use of encrusted polychrome marble was not typical of Renaissance architecture.



Dark green strips of marble outline the white marble pilasters and define large rectangles between them.


Superimposed rectangles. The rectangles on the lower story seem to divide the area into two distinct stories.  Flanking pilasters span both of these stories, making them appear to be of the colossal order.


Scale. The pattern of Santa Maria delle Carceri is simpler and on a much larger scale than medieval precedents.


Interior-Exterior Correspondence

There is a general correspondence between the interior and exterior.


Two-story division. On both the interior and exterior, the main block is divided into two corresponding stories.


Reversal of light-dark balance. The contrast between the pilasters and surrounding area is reversed from the interior to the exterior.  On the exterior, the white marble pilasters stand out against strips of dark green marble, while on the interior, the dark pietra serena pilasters stand out against white plaster walls.


Pilasters trimming corners. Pilasters are used to trim the corners of both the interior and exterior.


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