Las Vegas' Caesar's Palace
This one might be a bit of a surprise to readers as 1993's WrestleMania IX wasn't exactly a memorable show. At least, not for the reasons you'd want it to be (Hulk Hogan?). In fact, the show is often panned as one of the worst in the history of WrestleMania.
That being said, the set-up for WrestleMania IX was incredibly cool. It was the first time the show was held outside, and the backdrop of the Las Vegas strip made for some great visuals. WWE set this one up as the world's largest toga party, and signs were printed to look like Roman columns at the the top of the bleachers, the rig above the ring, as well as on the entrance itself, making for a unique set at a time when WrestleMania's sets were usually pretty stagnant.
Every WrestleMania prior to IX either featured no real set at all or just a WWF logo above the entranceway. WrestleMania VII went a little bit further with red, white, and blue signs on the concourse, though the entranceway itself was still pretty bland. WrestleMania IX changed the ball game from a production standpoint.