In February 2016, Robert Warren, the executive director of Hoyt Sherman Place, a historic mansion in Des Moines, Iowa, now used as a theater and meeting space, was looking for some Civil War-era flags to celebrate President’s Day. That’s when a staff member pointed him toward a store room under the theater’s second-story balcony. There, he noticed a large painting squeezed between a table and a wall. “I didn't think it was anything of value,” as Warren tells Mercedes Leguizamon and Brandon Griggs at CNN. “I wasn’t sure why it would’ve been in that closet.”

But what appeared to be an auction sticker on the back of the painting piqued his curiosity and Warren began an investigation. It turns out, the auction sticker was actually a tag from the New York Metropolitan Museum of Art, which once displayed the painting. The tag identified it as being by “Federico Baroccio,” ​which was, in fact, a mispelling of early-Baroque painter Federico Barocci. However, art scholars ultimately deduced that the painting was not by Barocci but rather its provenance dated back to the hand of Dutch master Otto van Veen, a teacher of Peter Paul Rubens.

“Otto van Veen, the artist, is in every major museum, the Louvre, the Portrait Gallery, the Rubens estate, and the paintings that have been sold have been valued between $4 million and $17 million,” Warren says in a CNN video.

According to a press release, the painting is called “Apollo and Venus” and was painted between 1595 and 1600. It depicts Venus as an artist painting the “Mountain of Love.” Next to her is Apollo, lyre in hand. A chubby little Cupid stands below Venus, clutching his miniature bow. The painting also depicts Venus’s painting supplies, as well as a collection of jewelry, a bowl of oysters, roses, and a basket of fruit and flowers.

Once Warren realized the significance of the piece, he sent it to art conservator Barry Bauman, a world-renowned restorationist famously known for restoring paintings for non-profits and museums pro-bono. In this case, Bauman spent four months meticulously cleaning layers of discolored varnish off the painting and resetting flaking paint. The finished product was unveiled in late March—where else but at Hoyt Sherman Place.

So why was a such a masterpiece tucked away in a remote storage area in the first place? According to CNN, the painting was originally loaned to the Met by a man named Nason Bartholomew Collins. When he moved to Des Moines, he took the painting with him. His descendant donated the van Veen and four other paintings to the Des Moines Women’s Club, which established the art gallery at Hoyt Sherman Place.

Warren tells Rob Dillard at Iowa Public Radio that he’s not sure why the painting was stashed under the theater, but has a couple of theories. “The assumption was it was tucked away there either because it needed some repair work or the content because it is a full backside nude of Venus de Milo and another cherub sans clothing,” he says.

In other words, it was a little risqué for the women’s club. “There were no other nudes in any other paintings in the collection,” Warren tells CNN. “It’s a very sensual painting.”

While the paperwork indicates that the painting was valued at $1,500 when it came into possession of the women’s club, it’s likely to be worth millions of dollars in today’s art market. But Warren says the historic home has no plans on selling the painting, rather it will hang in its art gallery once extra security is set up.