The room is 100' square and 10' high. There are no furnishings and the walls, floor and ceiling are all fashioned out of relatively smooth stone. Both the floor and the ceiling have a simple tile pattern applied to them, mirroring each other. Aside from the doorway through which the room is entered - a simple door-sized hole sunk into the wall - the only other feature is another door located on the opposite wall, the same in appearance as the entrance.
Operation & Stats
When the PC's enter the room, certain portions of the floor are pressure sensitive. Once stepped on, a corresponding section of the ceiling somewhere in the room will come crashing down - revealing itself to be a sold block of stone. Once triggered, the column remains where it has fallen, it will not reset while the PC's are in the room.
The white squares w/letters are the triggers, the dark squares are where the corresponding columns fall .
Options and Variations
To enhance this experience, populate the room with monsters who move around a lot, drawing the PC's further into the room and risking harm to their comrades. Skirmishers should work nicely.
Depending on how nice or cruel you are, you might want the monsters to know which tiles will trigger each section and use that against the PC's. The monster(s) could either already be in the room, or come rushing in when they hear the first rock column come crashing down.
Alternatively, you could use hovering and/or insubstantial monsters - Stirges or Ghosts, for example - who would not trigger the traps to draw the PC's attention away from where they are stepping.
Instead of simply having the doors slam shut to lock the PC's in the room until they 'solve' it, consider having the rock columns fall in front of the entrance and/or exit to the room.
Have a series of rooms like this, with the triggers and columns set-up in different locations. You could require that all the columns be safely triggered in one room before allowing the PC's to progress to the next. You might want to set them up in a meaningful pattern - at the same time, you don't want it to be too obvious which tiles are trapped and which are not.
Hide something in one (or all) of the rock columns.
The size of the room and the number of traps in it are easy to change.