Scheele's Gate

If you see a light green door at the end of the road, calmly walk back immediately and escape to a crowded area before the surrounding doors have turned light green together. Don't panic, be calm; if it knows you're panicking, there's no escape. That's all I can tell you - no one knows where exactly the green doors lead to. I was shopping with a friend one day; he did not pay attention and accidentally went through one of the doors. His phone never answered after that, and we never saw him again.

If it's a door near you that turns light green, leave that place immediately; if it's a door at the end of a hallway that turns light green, turn around immediately and leave the building you're in. DO. NOT. COME. BACK.

Announcement Regarding Internal Planning Adjustments at Longgui Library's Main Building (2018.4.7)
A post on a lesser-known anonymous discussion board
The scans of someone's diary entries
Announcement Regarding Relocation of the Main Building of Longgui Library (2021.6.22)
A WeChat screenshot