Eternal Ephemera is the first book dedicated to the visual culture and history of the possesso. This post-election procession led the pope from the Vatican to the Lateran, where he took solemn possession of his diocese as bishop of Rome. In this collection, six essays symbiotically expose the long-lasting ramifications of possessi in sixteenth- and seventeenth-century Rome. This triumphant parade affected architecture and urbanism, triggered new art forms (prints of the cavalcade or arches and chiaroscuro painting), and connected ephemera with the popular demand for moral economy. This volume innovatively shows the artistic and architectural legacy of the ephemeral in the Eternal City.