This is one my dad told me. When he and his brother were younger, they took a job to clean out some old ladies attic.The lady lived in a regular one story house with a normal attic space (the kind where you can't stand up fully, you have to stoop down and crawl everywhere). She had been hearing animals moving around, and wanted some of her stuff pulled out of there before it got chewed up. For some reason, the attic only had one crawlspace, and it was in the living room off to one side.

So they pulled up a folding ladder, put it underneath, and my uncle climbed up and pushed the door up. He popped his head through, and the attic, dimensions of space be damned, was an exact replica of the living room underneath it. Complete with lighting and doorways leading to god knows where. My dad was standing underneath, looking up he could tell something wasn't right by the light and the way the roof looked too far up, like getting vertigo.

My uncle closed the door, apologized to the lady, and they both took off. My dad said that his brother wouldn't talk to him until they were about a mile away. He just saw That look on his face, and when his brother said "we've gotta go", he didn't argue.