An unmarked brick warehouse on the west side of Atlanta has become the repository for some fifteen hundred works by more than a hundred African-American artists. Supervised by a seventy-four-year-old white man named Bill Arnett, it is the world’s most comprehensive collection of art made by untrained black Southerners. The warehouse, at first glance, may call to mind a salvage yard, for the artists used whatever materials were available to them: rocks, chains, clothes, rope, bedsprings, scrap metal, blood.