Art experts lost track of Auguste Rodin's bust of Napoleon in the 1930s. Little did they know the multimillion dollar sculpture was on display in a town hall building in Morris County, New Jersey, all along.

"Hello, my friend, so this is where you have been hiding," said Jérôme Le Blay, noted international expert in modern sculpture, upon seeing the Napoleon sculpture for the first time.

The marble bust was displayed in Madison borough hall for 85 years before it was revealed to be a long-lost artwork by French sculptor Rodin and worth millions of dollars on Wednesday.

The shocking origin of the bust — perched in the corner of the borough council chambers — was confirmed in the summer of 2015, but was kept under wraps for security reasons until Wednesday, when the owners announced it will be leaving town on loan to the Philadelphia Museum of Art.

The authentication was made in person by Le Blay, formerly of the Rodin Museum in Paris.

Le Blay said to the mayor of Madison: "You've been living with this thing for 85 years and you have no idea what you have?" said Nicolas Platt, president of the Hartley Dodge Foundation, which as part of an arrangement with Madison, owns the many artworks on public display in borough hall.

"I'd always heard the rumor it was a Rodin, but of course you hear all sorts of rumors. So to have it actually verified was quite impressive," Madison Mayor Robert Conley said. "To think that we've had people walking past it for years, not realizing the great piece of art they were sitting next to, or standing next to during a council meeting."

Philanthropist Geraldine R. Dodge purchased the circa 1908 sculpture some time after it had been exhibited at the Metropolitan Museum of Art in New York, from 1915 to 1929. She is believed to have donated it along with other artworks for public view in borough hall in 1942.

The origin of the bust faded from memory over time.

Former Madison historian, Larry Taber, had long believed it to be a genuine Rodin, "but it was never substantiated or confirmed by the Rodin Museum or the trustees," said Madison Administrator Ray Codey.

But when the Hartley Dodge Foundation hired Mallory Mortillaro, an art history student at nearby Drew University, to update the catalog of art in the building, she quickly closed in on the bust, believing it to be a Rodin.

"Right away, I saw the signature, and the piece characteristically fit in with Rodin," said Mortillaro, now a public school teacher in Summit. "But it was really once I was able to get in touch with Jérôme Le Blay — he's the Rodin expert of the world — and when he wrote back to me instantly, and with such enthusiasm, I knew we really had something. Hearing him say they had lost track of this piece since the 1930s, and didn't know where it was, that was pretty great."

Mortillaro said Le Blay declared it to be a Rodin with a letter of inclusion shortly after his visit to Madison.

Platt said he learned of the verification a few months later when the Rodin Museum in Paris sent him a photo of the artist himself, with the statue, and a note that stated simply, "Merry Christmas."

The discovery presented security concerns for the foundation and Madison, so officials said they decided to downplay the bust until a suitable disposition could be found. Experts say it is estimated to be worth between $4 million to $12 million, depending on art-market fluctuations.

"We couldn't shut the room down and we couldn't get enough insurance to cover it," said Platt, who also is a councilman and former mayor of neighboring Harding. "We had to get it out of the building and protected, because otherwise, we would have had to come up with special security, move the piece out of the council room and lock it away under guard."

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Platt is the godson of Marcellus Hartley Dodge, husband of philanthropist Geraldine Rockfeller Dodge, who deeded the magnificent Hartley Dodge Memorial building in 1935 to be used as Madison's municipal hall and courthouse.

The foundation finally found the ideal destination at the Philadelphia Museum of Art, where it will be part of the large celebration centering around Rodin’s art on the centennial of his death on Nov. 17.

But before the roughly 700-pound, slightly larger-than-life-size bust is transported out of the building, the foundation is inviting the public to a formal viewing Oct. 21 from 10 a.m. to 3 p.m. and Oct. 22 from 11 a.m. to 3 p.m.

Platt is unsure when the Rodin may return to borough hall, saying the Met has expressed interest in exhibiting it after it leaves Philadelphia.

"It will travel for a while, but we will never sell it," Platt said. "Even though it is owned by the Hartley Dodge Foundation, it belongs to Madison. Geraldine Rockefeller Dodge meant it to be a Rodin that was connected to Madison."

"Art is meant to be appreciated, and the more it can be appreciated the better," Conley said. "If it comes back after its loan time, we will need to make sure we treat it accordingly and protect it, but also allow it to be seen."

Staff Writer William Westhoven: 973-917-9242; wwesthoven@GannettNJ.com.