While digging in a large Roman house in the Spanish city of Mérida, archaeologists uncovered a vibrant mosaic featuring geometric and plant motifs, depictions of fish and animals, and, at its center, the head of Medusa. The mosaic covered the floor of a room measuring about 20 by 30 feet that had colorful painted walls. “Because of its location, we believe that this space was the tablinum, one of the main rooms of the house, where the owner received his guests,” says Félix Palma García, director of the Consortium of the Monumental City of Mérida.

Images of theatrical masks, a panther, and four peacocks frame Medusa. These symbols are associated with the god Dionysus, according to art historian Irene Mañas of the National University of Distance Education. Such mythological motifs were common domestic decorations in the late second or early third century A.D., when the mosaic was created. “The mosaic’s symbols and allusions have a protective sense,” Mañas says. “Medusa is an apotropaic image that would have protected the house’s inhabitants from the gaze of the envious.”