&lt;p&gt;If Detroit does take its artwork to the auction block — which some philanthropists and foundations are trying to prevent — then this piece might sell for $20-$40 million, according to Christie&#039;s.&lt;/p&gt;&lt;p&gt;&lt;em&gt;Dancers in the Green Room, &lt;/em&gt;Edgar Degas, c. 1879, oil on canvas.&lt;/p&gt;