D&D General Name a great dungeon room, trap, encounter, or puzzle from a published adventure (any edition)

[Lanefan]

I always loved the kitchen in A2 - Secret of the Slaver Stockade. It wasn't that the room itself was anything particularly special. But the encounter in it - with Icar fighting from the fire pit, the wereboars, and the hobgoblins - was evocative and fun.

And then you'd open the closet...