
Basically, the "Radiator Building — Night, New York" was given to Fisk University (an historically black school in Nashville) by Georgia O'Keeffe's husband's estate as a gift. Part of the terms of the gift were, as I understand it, that the artwork be shown at all times. The O'Keeffe Museum sued the The University for violating this term after Fisk reneged on their agreement to sell the painting, as well as rest of the 4-piece collection, for $7.5 million.
Why? They got a better deal, courtesy of Wal-Mart. http://www.santafenewmexican.com/news/68289.html