The phrase "nondescript building" refers to a structure or construction that lacks distinct or noticeable features, making it appear very ordinary or unremarkable. Full definition
We met in an unadorned conference room at Amazon's fast - growing campus of nondescript buildings. (thekindlechronicles.com)
IN A quiet backstreet in central London, not far from Buckingham Palace, a small, nondescript building hides the entrance to an unusual tunnel. (newscientist.com)