Perspective, Illusion and Devotion. The Chapel of S. Agnese in Sant’Agnese in Agone

Although built over many decades and through the intertwined and often indistinguishable work of many architects, artists, and craftsmen, the Church of Sant’ Agnese in Agone offers a coordinated system of artworks and illusory devices that were conceived to move the viewer physically and emotionally along preordained paths. This system reaches one of the highest moments in the Chapel of S. Agnese (Fig. 1), where the architectural structure and the sculptural apparatus are mediated by a bas-relief with illusory perspective. This work is a typical example of Baroque artistic practice in the second half of the 17th century, when theatrical conceptions transformed the interior of churches through the depiction of events frozen in their most dramatic moment and optical illusions and perspective devices were assigned a central role in altering the perception of space. The quality of the perspective relief, its intrinsic connection with other parts of the church, and the lack of information on Costanzo de Petri, the mysterious artist who rendered it, solicits a reconsideration of the historical and artistic context in which the Chapel of S. Agnese was conceived and realized. A recent topographic and photographic survey allows us to determine Costanzo’s contribution to the chapel’s decoration and the geometry he used to create his perspective bas-relief. It also elucidates the meaning of the work within the context of St. Agnes’ martyrdom.