"I didn't think it was anything of value," Robert Warren, executive director of the Hoyt Sherman Place art complex in Des Moines, Iowa told CNN. "I wasn't sure why it would've been in that closet."
Turns out, the painting is the work of 16th-century artist Otto van Veen and it's likely worth anything between $4 million - 11 million.
The painting depicts the mythological figures of Apollo and Venus along with her son Cupid.
"Venus, the Roman Goddess of Love... is portrayed as an artist painting a landscape... Apollo, holding a lyre, is the Roman God of Music, Poetry, and more. Cupid is the Roman God of Desire, Affection, and Erotic Love," explains the art gallery on its official website.
But the painting was likely never displayed to the public in Iowa. Mr Warren told WTHR there was probably objection to the nudity depicted in the painting when it was received back in the 1920s.
The gallery says the painting was "coated with layers of discolored varnish and former restoration work that flattened the three-dimensional quality of the scene... The surface was heavily overpainted after a succession of former restoration attempts."
It took experts four months to return the painting to its "pristine" appearance.
"I was a little surprised... in a room filled with junk I had no idea that it was as valuable as it turned out to be," Mr Warren admitted to WTHR.
The gallery has put the painting on display for the public. It has no plans to sell the artwork.
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