Its likely you have some memory of this awesome Keep from your early (1980s) D&D gaming. Here is an Alternate Keep. This Castle Caldwell is in fact an ancient Gate Keep that allowed movement of travellers through the 140 feet high/30'thick Shield wall that for our purposes encompased some ancient estate. This allows us to relate a number of different ruins across the region to one another.
LEVEL 1
LEVEL 2
LEVEL 3
LEVEL 4
LEVEL 5
LEVEL 6
LEVEL 7
LEVEL 8
LEVEL 9
LEVEL 10
THE DUNGEONS OF TERROR
Gaining access to the Dungeons of Terror through the Trap Door is now far more interesting. The Trap Door is now on an upper floor of Caldwell Castle making it a Magic Portal that transports the User one way to the Dungeons of Terror. The Dungeons of Terror can now be located any where. They could be thousands of Miles away. For Our purposes -
Area 1: A subterranean Cavern being converted into a Dungeon. This could be located under some Mound or Hill several miles from the Castle itself.
Area 2: Accessible by Teleport Circle. This allows us to have this Crypt area beneath the Graveyards of the Local Village/Town.
Dungeons of Terror Area 1
Dungeons of Terror Area 2
Thanks for the trip down memory lane.
UFO VERSION
This Castle Caldwell is A UFO long ago landed in a Rural Backwater.
It has 8 'Goblin'crew, a Robot Pilot (the Statue), and the Teleport chamber (Trapdoor) which makes the Dungeons of Terror the cavern where they have been mining dylithium.