Sotheby's International Realty
The commodities trading executive originally bought the property $1 million in the mid-1990s - when the modernist housing market had fewer buyers.
That said, John Hersam, one of the realtors in charge of the project, said Gallipoli likely spent much more to restore the property than it's current asking price.
"It was more of a project of passion, he didn't really think about the return," Hersam said. Hersam listed the property along with Inger Stringfellow.
According to the Wall Street Journal, living inside feels like living in a "tree house," said Gallipoli, who now lives in New York.
The property is a contemporary collector's dream: it's stayed true to Johnson's original design with changes to decrease energy inefficiencies: heat-insulating glass panes and floor heating.