The encyclopedic maps of Giovanni Battista Piranesi literalize the metaphor that “the map is the encyclopedia.” This essay compares two of his heavily annotated maps to the French Encyclopédie: where Denis Diderot and Jean le Rond d’Alembert theorize the map and the cross-reference as methods of organization, Piranesi employs both. With their references to annotated images, Piranesi’s encyclopedic maps ultimately expose the disorder and multiplicity hovering beneath the ordered objectivity of literal and figurative expressions of Enlightenment cartography. Additionally, this essay argues that his works are a productive site through which to consider aims and strategies of digital design.