So why is that the inspectors tend to prefer staying on the first floor? Well...it probably has something to do with the way one gets upstairs—which has nothing to do with stairs! From the first floor to the second floor of 2524, there is a ladder. To get to the third floor and above, one climbs out a second story window onto the fire escape and walks up (using the fire escape).
The only way to get access to an upper floor of 2526 is to climb the ladder from the first floor to the second in 2524, then climb out a non-fire-escaped window and walk across a three-foot-wide roof ledge between the two buildings. From there, one crawls through a window into the second floor of 2526. The fire escape is then used to proceed further "upstairs."
In the foreground of the photo below is the ladder that currently serves as the only access to the second floor of 2524 (and, technically, the only route to the second floor of 2526, as well). In the background, and in the two subsequent photos, you can see the mangled steel-frame staircase that used to run up the five stories of the building.

