Well. Not the _first_ time.
> It is not only the first time in 2,000 years that the area -- described as the "heart" of the building -- has been open; since the underground levels, or "hypogea," were where gladiators and animals waited before going into combat, this is the first time in the monument's history that the public has ever been allowed in.
"A small portion of the hypogea was opened to the public in 2016."
I've visited twice, and on the more recent occasion we found one of the few tours that offered this as part of the tour.