Santa Maria Maggiore and the Depiction of Holy Ground Plans in Late Medieval Italy

Several medieval building miracles feature plans marked on the ground in dew or snow, which can be understood as acheiropoieta, works not made by human hands. Despite a textual tradition dating back to the ninth century, the earliest depiction of such a plan may be that in the late medieval facade mosaics of Sta. Maria Maggiore in Rome. Three catalysts for this innovation are identified here: the legend, which combined a plan in snow and foundations that opened by themselves; institutional rivalry, as expressed in representations of church foundation and possession of miraculously created images; and increased ecclesiastical involvement in the initial stages of church construction, including delineating the foundations. In turn, the mosaics inspired further depictions of the miraculous plan and set a precedent for visualizing ground plans more widely in late medieval and early modern Italy, since illustrations of foundation rituals in pontificals arguably draw on images of the miracle of the snow. Examining this legendary and liturgical material together indicates that the plan and foundations of a church formed a key point of encounter between its construction and its spiritual significance. It also reveals a type of ground plan—an image of a plan marked on the ground—that can be distinguished in form and associations from other small-scale plans. Simple, schematic, and often cruciform, it was redolent of miraculous and sacred foundations. More broadly, the article demonstrates the potential of ephemeral marks on the ground to inform lasting visual and verbal representations in more conventional media.