The Rome's Colosseum's underground levels; the 鈥榟ypogea' (hypogeum; hypogea; Hypogaum; Colis茅e; Kolosseum) has been restored and is now open to visitors for the first time. The structures; located below the arena and that in ancient times was invisible to the spectators; consist of walls delimiting corridors; 8 longitudinal and 6 annular. The Colosseum; which could accommodate between 50;000 and 75;000 spectators; was equipped with a series of technological devices used for the appearance of men; animals and stage equipment on the arena. Among the devices dating back to the Flavian age; it is still possible to see the sequences of elevators housed in the corridors of the underground area. They are respectively 24 mobile platforms and 28 wooden elevators containing cages raised by winches. Until 523 AD; the year in which record indicates the last show; spectators could not enter the hypogea and access was possible through 4 underground galleries. The project; which began in December 2018 has focused on the Colosseum's hypogea; a monument within the monument; corresponding to the portion of the amphitheater which lies below the arena and that in ancient times was invisible to the spectators. At the end of the works; a 160 metre long walkway was installed in the Colosseum; opening up to visitors an area of the monument that had never been accessible before. Rome; Italy. 8/2021.