I don't remember seeing those sand dunes (assuming that's what they're supposed to be) in 2-2. I always just thought the bridges were way up in the sky and those pillars were giant obelisk thingies, kinda like the four towers in Tower of the Wing Cap.
Also, I'd like to take this moment to say 2-2 and 7-2's background is my absolute favorite thing in the All-Stars version of SMB.