Does the Arch of Constantine in Rome have an interior? (I'm not speaking of the empty space formed by the arch itself, but rather of the massive stone structure which forms the arch.)
The Wikipedia article on the Arch claims, without citing any sources, that "[a] staircase within the arch is entered from a door at some height from the ground, on the west side, facing the Palatine Hill." If this is true, what is at the top of the staircase? Does it lead directly to the roof, or are there any interior rooms? Is there a corresponding staircase down the other column? Where can I see photographs of the door and of the interior?