What is your favorite spefic detail/ room thingie in doom wads?

Grungo like barrack style rooms where there are individual rooms with beds and doomcute, and potentially goodies and secret doors and vents inside

always makes grungo excited

My favourite aesthetics of maps are wood-paneled libraries (e.g. Doom II MAP27) or bricked, hellish temple-like structures (e.g. Freedoom: Phase 2 MAP25), there's something about those I find strange but awesome.

sincerely, multi-tier crate mazes

Things that blow up like this fuelpod...