Keep on Mountain Pass (2004)

From the Introduction:

Huge and impressive, this fortress rises between two massive mountains. The fortress features 13 known levels, two of which are
below the surface level. The level “0” has two gates with guardhouses, a road passes through the fortress. The subterranean levels
are the dungeons, complete with torture chamber and cells. The levels from 1 to 10 feature barracks for soldiers and officer’s
rooms. The higher level houses the lords of the keep and their families. Some hints to use the keep follow:

• A legendary stronghold guarding a mountain pass, occupied by a strong garrison of the royal army.
• A goblin infested ruined keep; the goblins attack any caravan passing through the ancient walls.
• An ancient keep now haunted by spectres and undeads, a lich is said to live under the dome on the upper level.
• An ex-fortress, now useless, because the nations live in peace, and therefore transformed in a huge marketplace.
• A ruined keep, now hideout of a famed bandit who assaults nearby territories