Interior, showing an underground chamber reached by two flights of stairs, one on each side; niches on the landing above, from "Speculum Romanae Magnificentiae" Wall Art

"Interior, showing an underground chamber reached by two flights of stairs, one on each side; niches on the landing above, from "Speculum Romanae Magnificentiae"" by Anonymous, 16th century. Engraving. Original high-resolution public-domain artwork from The Metropolitan Museum of Art.