Been a couple years--I think nothing tho. The original plan was a South/Central American folklore house in the building that became Transformers. When that was taken off the table, had to scramble to add capacity to the event. I want to say that was the first year they used the parade building (obviously worked well enough to become a staple). I'm sure Dr. Jimmy covers the whole thing in detail in his 2012 history videos.
Just barely beat me to it.
Supposedly they had actually begun construction on the house when the order came in to knock down the building. Haven't heard it from an official source though, so as far as I know that's just rumor. They had used the other side of the parade building every year since 2008, but 2012 was the first year they flipped to the other side.
I'll be curious to see whether its home to an original or IP this year.