When Mount Vesuvius erupted in 79 C.E., the enormous explosion buried the city of Pompeii in an astonishing 19 meters of ash and debris. (A recent study concludes that in the neighboring town of Herculaneum, the blast was so intense that it vitrified a young man’s brain.) Since excavations of the area began in 1748, discovery after discovery has revealed lavish, poignant, and complex details about what life was like nearly 2,000 years ago in the Roman port town.

When Vesuvius buried everything, the ash provided an extraordinarily protective covering for delicate frescos and structures, like an expansive fresco recently excavated in a banquet hall that “sheds light on the mysteries of Dionysus in the classical world,” says a statement from Italy’s Ministry of Culture.

The large-scale painted frieze archaeologists are calling “house of Thiasos” shows the procession of Dionysus, god of wine, along with satyrs and bacchantes—also known as maenads—who are portrayed simultaneously as dancers and hunters.

In the center of the composition, a woman is accompanied by Silenus, an elderly companion and tutor to Dionysus, holding a torch. The woman “indicates that she is an initiand,” the Ministry of Culture says, “a mortal woman who through a nocturnal ritual is about to be initiated into the mysteries of Dionysus, the god who dies and is reborn and who promises the same to his followers.”

Spanning three walls of a building—the fourth had been open to a garden—in the so-called Regio IX district, the painting depicts a frieze known as a “megalography,” derived from the Greek for “large painting” and comprising a cycle of paintings with nearly life-size figures. Archaeologists date the fresco to around 40 to 30 B.C.E., nearly 100 years old already by the time Vesuvius erupted.

Archaeologies typically categorize Roman and Pompeiian painting into four chronological periods or styles: incrustation (structural), architectural, ornamental, and intricate. Each style adapted elements of the previous period to generate new motifs and trends.

The new banquet hall example is thought to be indicative of the second style in which figures or tableaux are framed within faux architectural niches and trompe-l’œil compositions. Curiously for art historians, all of the figures are depicted on pedestals “as if they were statues,” the Ministry of Culture says, “while at the same time their movements, complexion, and clothing make them appear very alive.”

Investigations into the Regio IX district, which covers approximately 3,200 square meters, began two years ago. So far, the excavation of the entirely buried block has revealed two atrium houses—already partially explored in the 19th century—plus two workshop houses, some residential rooms of a large domus, a black hall with scenes from the Trojan saga, and a shrine with a rare blue background. More than 50 new rooms have been identified, and there is plenty more yet to uncover.

As archaeologists gradually chip away at the ancient pile of volcanic detritus, new finds like a food stand and a primitive pizza continue to awe and inspire our understanding of ancient Roman life. The site is open for public visits, and you can explore more on the Archaeological Park of Pompeii’s website.