For me, I've always called it the "school at night" phenomenon. The horror, or unsettling feeling, one gets from seeing a place at night that's usually only seen in the day. Had that constantly as a kid when going to school at night for performances or teacher meetings. A place bright and loud that's now quiet and dark. You know where everything is, but it all seems like it's just an inch or two out of place.

The other aspect of "creepiness" stems from the idea that the Backrooms represent an endless, malevolent labyrinth. One of the scarier aspects of being trapped in the Backrooms (for me) is that you would just wander around until you died for lack of water and food, in a bland corporate office corridor with fluorescent lights buzzing overhead.

I think this is just how things evolve. Creepy is a very strong sentiment that is somewhat aligned with uncanny, so it isn’t that surprising to see uncanny collapse into it over time.

But having spent a lot of time in empty classrooms, auditoriums, and hallways, waiting for students to show up, it’s more of a nostalgic feeling to me.

I'm not sure if that's true. I've definitely been to places that feel intentionally confusing; the basement of my college, several hospitals, etc. Where you walk between two buildings, and suddenly go from Floor 4 to Floor 6, or where you're sure you entered facing north, but after making three right-hand turns, you exit a building facing south.

I developed a fondness for 1970s interior decor/styling even though I was born in 1988 because most of the places in my town, such as the library, were last renovated during that time.

Also, many people in my life, such as uncles & aunts, were still living in the homes they purchased in the 1970s and some design choices just can't be easily/cheaply changed.

I grew up within and around a ghost of 1970s architecture and design. As an adult I wound up moving into a suburb built in 1968 for this reason.

It's less nostalgia and more like a vague sense of familiarity that you can only scratch the surface of in your mind.

You could look from one end to the other, seeing a series of doorways, and then walk through them all; every time I walked from one room to another, by brain would do a little power cycle as it tried to deal with the sensation of having walked into the room I'd just exited.

The deeper-in I got, the more I couldn't shake the feeling that something was "off" about the whole set-up; there were windows, but looking out them, the view felt... fake? It's hard to describe.

This was a few years after SCP became popular, but before the Backrooms - which was why I immediately understood the appeal.

My teenage daughter is really into this genre but has never actually been in a mostly abandoned 90s mall or fluorescent-lit business park office space herself.

But don't underestimate how much history bleeds forwards in time in various bits of cultural ephemera that can still be absorbed by younger people. She doesn't have much first-had experience with spaces with this vibe, but there is ample second-hand media of it and enough bits and pieces of it still in the real world for it to be both somewhat familiar and enticingly exotic to her.

Also, the infinite corridors is only part of the appeal. There are other ways in which such spaces can become eerie. I remember how I used to often be the only person still working in an open floor plan office in the evening. There was no sense of infinite corridors, but the dimness with one area alone illuminated by motion-detected light was spooky, and so were the sounds of the HVAC system and of doors and elevators somewhere in a different part of the building. There was also an uncanny empty feeling of seeing all the chairs and desks with no humans at them.

That's kinda more what the german concept of "unheimlich" is like. Even though it usually gets translated to English as "uncanny", it's more literally "un-homelike", when the familiar (home) turns unfamiliar (un-homelike) in an unexpected way. A common idea in that would be something like the discovery of a hidden room in your house, especially in some weird non-euclidean way ("it's bigger on the inside" for example, like a tardis).

During the 60s and 70s, in order to accommodate baby boomers, new buildings were built on existing school grounds, and while they were not cookie cutter copies of each other, they followed the same architectural and civil engineering principles: identical ceiling height, same fixtures, same walls, same classroom door arches, same bathroom stalls, toilets, similar fire exit paths, identical heavy steel and steel wired glass external doors, staircase layouts...

But given every location had its own available surface and urban/terrain/attendance needs, they were anywhere from 1 to 4 floors, straight corridors, or in L, or rectangular with inner courtyard, with and without basement, and overall significant practical deviations from some common standard blueprint (though I never found the common denominator) but keeping everything else the same. It was extremely eerie and disorienting visiting a different school, or getting used to another school when you moved, especially after hours when they're empty.

It's probably similar to the khrushchyovki/stalinki residential buildings in post-Soviet countries, though I've only visited them well after the collapse and they've evolved on their own. Meanwhile these schools I mention, look actually frozen in time.

https://www.sciencefocus.com/the-human-body/anemoia-nostalgi...

I watched the film Asteroid City last night, and the setting gave me this exact emotion.