The last of Victor and Sally Ganz’s seven Robert Rauschenberg combines is finally coming to market. The Tower from 1957 is the only one that hasn’t made its way to a museum because it was not sold in the famous 1997 Ganz sale at Christie’s.

Now it is being sold and estimated at between $12 and $18 million. If it sells toward the middle of the estimate range, the work will make a record price for Rauschenberg whose most expensive work was a little more than $14m in early 2008.