Designing in the Baths of Caracalla - Is it possible to design permanently inside a monument with extraordinary iconic power, even if (but perhaps especially if) it takes on the sublime image of a Ruin? And furthermore, are we able to enter into a dialectic with the great symbolic and spatial force of the monument, positively inserting our culture, our experience and therefore also a new reading and use of these great historical complexes? Every time you enter the Baths of Caracalla, you try to imagine where the water that animated it was in ancient times. Water for swimming, for physical activity, where you could spend a day dedicated to wellness. Where was the water? How did the many visitors to the Baths move, between pools and fountains? What did they do? In fact, they practiced Otium to take care of themselves in body and mind, in the pools and gardens, walking under the Peristyle or stopping in one of the two Libraries. The large water mirror (42 x 32 meters), which reflects the majestic architecture of the baths, is the first strong sign of contemporary architecture aimed at triggering a process of redevelopment of the archaeological site into an urban park integrated into the fabric of the city. A pool with a linear shape, which intentionally takes up the proportions of the Natatio, simple lines that, in a play of presence and absence, put the monument and the visitor at the center, with a stage on the water that will have the function of hosting theatrical performances, conferences, dance shows or classical music concerts.