The Halfway to Heaven Inn is located in Heaven's Peak. The front half of the Inn is a tavern filled with (mostly drunken) civilians, some of whom challenging the Overlord to a bar brawl. Fighting them results in Corruption points.
The back half is a series of dank corridors eventually leading to the headquarters of the Order of the Red Dawn, and the lair of the Succubus Queen.
Tower Items:
Minion Totem - This is located behind a door in cult's first room.
Succubus Stone - Located in the Succubus Queen's room. Its benefits seem to be purely cosmetic.