Stage 13 appeared on the Upper Lot in January 2007. Along with Stage 52, its main function is to keep the feeling of being in a working movie studio. However, what's the story behind the choice of number? Isn't 13 supposed to be an unlucky number? As the current inhabitant of the stage is Universal's House of Horrors, then it all starts to make sense...
There is no Stage 13 on the front lot (nor any multiple of 13, so no Stage 26 or 39).

The building was originally the Marvel Mania restaurant, and until this paintjob, still had the blue walls and cartoony graphics from that restaurant (see photo above right).