[MichaelRyerson]

Yeah, an optical illusion. Happens to me all the time. And yes, the arches lead to the stairwells at 5th Street level and then up to the arches halfway up and back out to the exterior stair cases. I remember my father taking my brother and I someplace downtown with some regularity (I don't remember exactly where) and he would make a point of parking up above so we could come down through the sort of ornate stairwells. I think there must have been several such configurations around downtown. Now, of course, street crime would discourage most people from using them. More's the pity.