Underground is an unloaded keyword appearing on sites. It typically boosts the , and cultures.
Balin's Tomb
Dwarrowdelf Chamber
Great Chasm
Mithril Mine
Moria Stairway
The Bridge of Khazad-dum
Cavern Entrance
Caverns of Isengard
Caves of Aglarond
City of the Dead
The Dimholt
Abandoned Mine Shaft
Breeding Pit of Isengard
Chamber of Mazarbul
Moria Guardroom
Mount Doom
West Gate of Moria
Window on the West
, 
and 
cultures.
, and cultures.