Unknown. However food historians do have a fairly good idea of where and when the gingerbread house became popular: in Germany in the early 1800’s, not long after the Grimm Brothers published their collection of fairy tales. The particular tale that made those houses so popular was of course Hansel and Gretel. Apparently, in the years after the publication of the story, German bakers couldn’t make enough of the things. Since the Brothers Grimm didn’t make up the stories they published (rather, they collected them from older sources) it’s almost certain that the idea of the gingerbread house was around well before them. Just who it was who first conceived a house made of baked, sweet dough is a mystery.