"None Shall Pass!"
Here's a return to the Stonework and Statue series of geomorphs: S8, the Stone Sentinels. Two large statues of knights flank either side of a door. Whether one or both is animated or merely concealment for a trap, or just an innocent indicator of a special area, is up to the GM. Beyond the door are stairs up to a large room with no other obvious exits. However, there's a secret door on the opposite wall leading to a descending staircase. And below this room is a smaller, disconnected 20' square room.
As an added element of interest, there's a small hollow space skirting the room in the lower right quadrant. Could be a hidden treasure cache, could have some other significance, or could just be an annoying red herring.
The models that I use for many of these geomorphs, including the sentinels, don't look so well when enlarged and viewed from another angle. For example, see this sentinel? He looks a little less detailed than he should be, with chunkier body parts, some the wrong size. The intention eventually is to print out close-ups of the models to do hand sketches on top of them, then scan in the properly detailed versions. I haven't been doing this because my scanner and two non-functioning printers are in storage. I'll take care of that at some point and will then be able to do some better illustration.