Maybe, but you're seeing just the ceiling. If pictures of other areas of the structure are any indication, the actual floor is many feet below the level of the dirt fill.
For example...
It looks like a culvert with graffiti.
It appears to be an artificial grotto. It's amazing to me that the fire of Rome happened in 64 AD, and Nero ordered the construction of the Domus Aurea not long after it had burned itself out. The construction was rapid, and included the Colossus, a 90 foot statue of Nero, which was moved to a new location outside the Flavian amphitheater, which is why it is still called the Colosseum. And Nero died in 68 AD, a mere four years after the fire.
Maybe, but you're seeing just the ceiling. If pictures of other areas of the structure are any indication, the actual floor is many feet below the level of the dirt fill.
For example...