Day vs. Night are what makes the difference. The sprawling suburban office complex from the 70s was, like you said, just boring and a bit oppressive during the day. At night though, a sea of cubicles. Endless hallways. Nothing but blackness outside the windows. Lights are all on motion detectors so only your area is lit. And only lit for a time. Eventually you'd have to stand up to make the lights switch back on. And when you do, you look over the fields of cubes to see a shadowy figure slowly slump its way across the room. Headed vaguely in your direction but never quite reaching you. You think it's Mark from Accounting, but you'll never know for certain.

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.

>For me, I've always called it the "school at night" phenomenon.

It's funny, I've always loved that kind of environment. Quiet high school hallways after everyone's left, empty university buildings late at night, offices after hours, even empty offices that haven't been moved into yet. For me it evokes feelings associated more with watching a rainy day from inside, or lofi-girl with headphones studying.

I understand why it can evoke horror or unsettling feelings for people, but for me the first word that comes to mind is just "peaceful".

Even the environments in the Backrooms trailer - minus the obvious horror elements - look like they would be a lot of fun to explore!

I agree, it's the night-time that makes places, particularly urban ones unnerving and/or creepy. I once worked as a courier, which sometimes involved delivering things to stores or weird ass storage buildings in the middle of the night. I hated those night-time deliveries. Even worse when I had to go through rooms with mannequins, made my skin crawl.

The smell of old cigarettes, stale coffee, Certs, and urinal cakes wafting through the air.