where am I? (the backrooms)

Info:
One day I was just talking with my friends, as usual, but when I tried to lean against a a wall, instead of feeling pressure on my shoulder, I felt nothing and I fell through the wall, where am I?

TW: there will be mentions of blood, gore,
Dead body's and just scary stuff in general, so if you're sensitive to content like this then I'd recommend reading something else.