An 18th-century painting looted by the Nazis more than 80 years ago has been unexpectedly recovered — after it was spotted in a real estate photo of the Argentina home of a Third Reich official’s daughter.

The portrait of Contessa Colleoni by Italian artist Giuseppe Ghislandi hadn’t been seen in public since it was stolen from Jacques Goudstikker, a Jewish art collector, in Amsterdam back in 1940.

Then an online real estate listing in the coastal city of Mar del Plata changed all that.

The portrait of Contessa Colleoni by Italian artist Giuseppe Ghislandi was spotted last month in a real estate listing in Argentina. Robles Casas & Campos

Police show items recovered in the Argentina home. Policia Federal Argentina.

The painting unexpectedly exploded back into public view when senior Nazi official Friedrich Kadgien’s daughter listed her villa for sale last month — with the Italian masterpiece on full display in a living room.

Eagle-eyed Dutch reporters tipped off authorities after spotting the artwork in the listing when they were investigating Kadgien’s ties to Argentina.

Kadgien was a senior official in Adolf Hitler’s government who fled to South America from Germany after World War II. He died in 1979.

Argentine cops last week raided the villa — which is currently owned by Kadgien’s daughter, Patricia Kadgien, and her husband — but weren’t immediately able to locate the painting.

The painting unexpectedly exploded back into public view when senior Nazi official Friedrich Kadgien’s daughter listed her villa for sale last month.

“We had indications that the painting might be in this residence,” Argentina federal prosecutor Carlos Martinez said after the raid.

“The painting wasn’t in the house, but we seized some documents related to engravings and drawings that might provide context.”

“At the moment, we have two individuals under investigation — owners of the property linked to possession of the painting,” Martinez added at the time.

The couple’s lawyer later handed the iconic painting over to the prosecutor’s office.

Argentine cops last week raided the villa — which is currently owned by Kadgien’s daughter, Patricia Kadgien, and her husband — but weren’t able to locate the artwork. AFP via Getty Images

Patricia Kadgien and her husband were placed under house arrest earlier this week as authorities probe whether they may have obstructed the effort to locate the painting.

It wasn’t immediately clear what, if any, charges they could face.

With Post wires