The unexpected discovery of the ruins of a Roman theater after the demolition of some buildings in the historical center of Cartagena was the seed of this project. The aim was to reincorporate the long-lost theater into the city. The museum sensu stricto solves the matter of access into the Roman theater. The main entrance is located on Town Hall Square via the late 19th-century Riquelme Palace, which contains the library, administration, and service rooms. Underneath a street, a corridor showing some Roman remains leads to a gallery where the most important pieces found during the excavations are exhibited; here, escalators take visitors to the upper levels. Then, underneath the Church of Santa María La Vieja, a dramatic display of archeological remains illustrates what the city of Cartagena once was. Finally, upon entering the Roman theater, the museum reaches its climax. This intervention incorporated the theater into the nearby park, facilitating an understanding of what the city was in the past, and allowing the dense old town to breathe without losing its character.