A renovation at Paris’s Ritz hotel has resulted in the discovery of a painting thought to be the work of 17th century artist Charles Le Brun that nobody knew was there.

Now, the giant tableau is to be sold by Christie’s auctioneers and could raise up to 500,000 euros ($665,000) for the foundation established by owner Mohamed Al Fayed in memory of his son Dodi, the late boyfriend of Princess Diana.

The oil painting has been identified by experts as an early work by Le Brun (1619-1690), completed before he became the official painter at the court of Louis XIV and established his reputation as one of the dominant figures of 17th century French art.

It adorned one of the suites in which Coco Chanel lived for more than 30 years but when exactly it was installed in the hotel remains a mystery.

The man who first spotted the painting was Olivier Lefeuvre, a Christie’s France specialist in the period, who came across it in July, a month before the Ritz closed its doors for a two-year renovation.

The painting depicts the killing of Trojan princess Polyxena after she was implicated in the death of Achilles. In the absence of any historical records, Christie’s have named the painting as “The Sacrifice of Polyxena.”

According to Lefeuvre, Le Brun most likely painted the scene after a three-year stay in Rome where he studied the work of Raphael and became close to Poussin.