While making routine repairs to the historic Prince’s Palace of Monaco in 2015, restorers made a surprising discovery: a series of hidden frescoes depicting the 12 labors of Hercules and allegorical figures that had been covered with paint for centuries.

After years of careful preservation by a team of roughly 40 specialists, the frescoes are finally ready for prime time, reports Artnet’s Jo Lawson-Tancred. Officials had planned to unveil the paintings in 2020 but were delayed by the Covid-19 pandemic. Now on view as part of the palace’s summer reopening, the frescoes are accessible to the public through October 15.

Initially conceived as part of a Genoese fortress in 1191, the palace has served as the home of the Grimaldi family since 1297. Today, it’s the residence of Albert II, who became the 32nd ruler of the small, sovereign principality located along the Mediterranean Sea in 2005.

It’s unclear who covered up the frescoes in the first place—or why—but experts believe they likely date back to the 16th century, during the Italian Renaissance. They suspect Genoese artists created the frescoes, which span around 718 square yards, based on the style of the art and the type of lime-based plaster used.

The discovery places both the Grimaldi family and the building itself “within a new art historical context as a Renaissance palace,” Julia Greiner, the chief conservator-restorer, tells Artnet.

In addition to Hercules’ labors, restorers also discovered a large fresco of Odysseus and a ceiling painting depicting the mythological abduction of Europa by the god Zeus, who appears in the form of a bull.

“This scene is depicted here with sweetness and poetry,” palace officials wrote of the Europa piece in a Facebook post, according to Google Translate. “The chromatic range, extremely well preserved, recalls the Mediterranean sunsets and the rosy cheeks of the young woman. The movement of the water around the bull is extraordinary in life and accuracy.”

Monaco is the second-smallest independent state in the world, after Vatican City. Situated on a rocky outcropping within a natural harbor of the Mediterranean, the site of the palace served as a strategic outpost for the Republic of Genoa starting in the late 12th century. The Grimaldis, one of the aristocratic families of Genoa, captured the fortress in 1297. Over the years, as age and various battles have taken their toll on the property, the family has undertaken many renovation and expansion projects.

As Cassandra Tanti writes for Monaco Life, today, the palace “reveals the changing tastes over time and is filled with beautiful pieces of art, painted ceilings and elaborately decorated spaces. Though certainly museum-quality, the rooms feel more accessible and livable due to the way they have been staged.”