A bridge becomes a mountain. Paper turns into rock. Paris discovers a hidden cave in the middle of the Seine. Trace the conception and creation of JR’s monumental installation La Caverne du Pont Neuf , a transformative work that reimagines the historic bridge as a vast rocky grotto. Freely accessible to the city’s citizens and visitors alike, but only fleetingly. Conceived as a tribute to Christo and Jeanne-Claude on the 40th anniversary of The Pont Neuf Wrapped , the project continues JR’s exploration of public art as a shared, democratic experience . Through preparatory sketches, collages, installation photography, and behind-the-scenes documentation , the book reveals how the landmark was transformed into an uncanny geological fantasy. The inclusion of earlier works featuring caves, trompe l’oeil, and architectural illusion situates this latest endeavor within JR’s headline-grabbing career. An interview conducted by Hans Ulrich Obrist with JR, Christo’s nephew and project director Vladimir Yavachev, and Thomas Bangalter of Daft Punk explores artistic freedom, ambition, and the challenge of realizing large-scale public works outside traditional systems of sponsorship and control. Ephemeral by nature, La Caverne du Pont Neuf is destined to disappear. This volume preserves the intertwined traces of its making while capturing the larger idea at the heart of JR’s work: that art can interrupt the day-to-day, reshape collective memory, and momentarily alter the way we see the world .