Looks to be a sales aid issued by TSR to retailers to promote the Menzoberranzan box set (1992), with the art being identical to the poster included in Menzoberranzan box set, except with promotional graphics:
Forgotten Realms Boxed Set – Discover Menzoberranzan, City of Danger – ON SALE HERE!
Plus the TSR logo and trademark language.
31.5″ x 21.5″, folded.
EDIT: Auction ended at $37.
EDIT 4/25/2020 The House Baenre compound
Listing a Menzoberranzan box set today. The House Baenre compound isometric map caught my eye, got some great photos. Cartography credited to Diesel.