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.