Within the densely packed fabric of the old city of Seville, the Plaza de la Encarnación was left empty after its nineteenth-century market structures were dismantled in 1973. When Roman ruins were found under the plaza, Seville’s government had to reconsider the significance of this pocket of land. It launched an international design competition for a project that would generate the kind of social exchange and commercial activity that the plaza had once provided the city. In Mayer H.’s winning scheme, mushroom-shaped growths shade the open plaza below, where a raised platform sits atop a new market hall, creating a stage for public events and a new hive of activity. Taking its cues from the vaults of Seville’s cathedral, the design fulfills the architect’s aspiration to create a “cathedral without walls” that would be “democratic” and also establish a unique relationship between the archeological past and the city’s contemporary uses.