The Colosseum reveals a side that hasn’t been seen for over a century. The Archaeological Park has reopened the southern ambulacra, two corridors on the south side that had been obscured by a 19th-century refurbishment that covered the original floor. After four years of excavation and restoration, this area is now open to the public in its original condition. The Park conceived the project, which was arranged by renowned architect Stefano Boeri, to restore Flavian travertine flooring to its original level. The new floor is designed to replicate the ancient blocks that were discovered during the excavations. In certain areas, the foundations and construction levels have been left visible, revealing the construction process of the Amphitheater. The investigations have also enabled the precise identification of the hydraulic system and confirmed the complex's dating to the reign of Vespasian. The Colosseum's south side, which was built on more unstable terrain, crumbled between Late Antiquity and the Middle Ages due to earthquakes, subsidence, and repeated material reuse. Archaeological research has documented over a thousand years of stratification, up to the major restorations of the 19th century. The new flooring, which is totally reversible and manufactured from materials compatible with the ancient ones, has restored the profile of the two lost corridors and offers a more complete reading of the monument. An area that was previously considered "external" is now an essential component of the visitor experience, which clarifies the Colosseum's architectural history and original symmetry.