There is a house somewhere in China built some time after the First Emperor had unified the nation. The house is built in treacherous terrain, and hasn't been seen by human eyes for some time. The architecture is typical of Imperial China, but that's not the important part.

If you stay in the house, you'll notice something very strange. If you take measurements, you'll find that the inside of the house is larger than the outside. First it'll be a fraction of an inch, than an inch, then a foot, then a yard... you'll even notice features from the inside that are impossible to find externally, like extra rooms and hallways. Going within these is safe, and you can see the outside, but strangely enough, no one outside the house can see you or the feature.

Most people get out at this point, but their vision is forever altered; the world keeps distorting in dimensions and size in their eyes. Then, there are those who choose to stay further, and have never been seen again. It is said that they occupy the parts of the building that only reveal themselves to those who stay longer.