I've added a new model to the dxContent 3D Dungeon Tiles collection I like to call the "Demon Gate".
In the following picture you can see the subtle markings of some long and forgotten evil on the stonework and the corroded metal gate.
This is actually a five piece set as this shot from my work area shows.
So there you go, a must-have model for any classic dungeon set. You can get it for $9.60 from the dxContent Tile store.