Lenko Cavem was possibly a resident living at "938120 Plateau Place" in North-South City.

Misreading "Cavem" for "Cavern" a former erroneous entry found in the 966 GUE edition of the Encyclopedia Frobozzica once read:
"Lenko Cavern is located in North-South City, somewhere in the Great Underground Empire."

SOURCE(S): Zork II (The GUE on 9 Zorkmids a Day), Encyclopedia Frobozzica