I took the original version of this photo (you can see it below) from the top of a rotunda in San Francisco City Hall. You can see a couple of people reading notices by a courtroom door, and the faint shadow of people in motion walking the corridors, rendered wraith-like by the long three-second exposure (selected so I could get plenty of depth of field).
The circular opening in the photo was actually pretty narrow, and the railing was high. The problem for me was getting my tripod in position over this balustrade. Even so, some tripod shadow and a tripod leg ended up in the capture, and I had to Photoshop them out.
With a decent rotunda view in hand, I pasted in four successively smaller (each copy was 20% of the size of the previous version) copies of the orginal image, to create a composite with the illusion of endless depth. This is the same technique I used in Endless Stairs and World without End.
As Phyllis says, “Down, down, into the pits of Hell, each a circle of bureaucracy lower in the pit!”
View this image larger.
[Nikon D300, 10.5mm digital fisheye, 3 seconds at f/22 and ISO 100, tripod mounted.]