This Doom 2 level is actually based on the level designer's house

A lot of people don't know that part of the Doom 2 level 16 map is based on the floorplan of the house that Doom designer Sandy Petersen was building at the time. I was among the people who did not know that, until I took this video tour of that exact house, delivered by none other than Petersen himself.

The house has changed a little bit over the years—it's been almost three decades, you know—but you can see in the split-screen video that it still matches up quite well with its in-game counterpart: The library, the microwave, and even the cacodemon are all right where they should be. The stairs don't work quite as they should—Doom was never very good with the Z-axis—but the garage is there, and appropriately loaded with demonic beasts as well.

This isn't the only real-world house that was recreated for the level. Petersen says at the start of the tour that "several" houses were made for it, and wraps up with a note saying that the house he grew up in, and where his parents still live, is also in the game. It's not as obviously spot-on as Petersen's own house, but yeah, you can see it.

Petersen, by the way, worked on games including Quake, Age of Empires, and Halo Wars in his post-Doom videogame career, and these days focuses on making tabletop RPGs and board games at Petersen Games. (In his pre-Doom life, Petersen was an employee of Chaosium and the designer of the 1981 Call of Cthulhu RPG.) 

If you don't have picture-perfect recall of Doom 2 level 16, you can see the whole thing in the walkthrough video below. The trip to Chez Petersen starts at 1:35.