it is indeed the Liberia Plantation, the address is sometimes listed as 8601 Portner Ave.
the latest Google imagery shows a new clearing in the trees near the house -- a visitor parking lot in the works, perhaps?
Annaburg is a few blocks to the west, between Sudley Rd. & Maple St.
http://wikimapia.org/5906619/Annaburg-Manor-1894