The shattered ruins of the “inverted ziggurat” below White Plume Mountain, littered with the moldering bones of creatures once bound within glass enclosures, slain by a party of adventurers many years ago  (Wayne Reynolds, Return to White Plume Mountain, TSR, 1999, after David Sutherland’s drawing of the intact room from the original 1979 AD&D module S2)

The cursed ruins of Castle Mukos — Who knows what lies within?  (it’s meenlocks, lots of meenlocks).  This is one of the locations first mentioned as a little detail on Erol Otus’ 1980 map from the original S2: White Plume Mountain, illustrated years later by Wayne Reynolds in Return to White Plume Mountain, TSR, 1999.