Did they know? Did the Romans living in luxury—drinking and dining to excess on marble floors in their extravagant villas in Baiae—know their precious homes would be submerged beneath the Gulf of Pozzuoli because of a volcano? Probably not.
Today, we know this because one of the flashy marble floors from Roman times has emerged from rubble on the seafloor in what is now a large site of submerged ruins called the Underwater Archeological Park of Baiae, off the coast of southern Italy. Here, beautifully preserved mosaics and other ancient remains have been found.
Underwater archaeologists observed a style of inlaid marble floor called opus sectile over an area of about 2,700 square feet in Baiae. Comprising a basilica plan with an apse, the style is typical of the period between the 3rd and 5th centuries A.D., according to the Archaeological Park of the Phlegraean Fields.
Arranged in a grid pattern, the floor sprawls some 20 squares wide and 30 squares long for a sum of about 600 squares. Each rhombus shape measures about 24 by 24 inches (60 cm by 60 cm), or two Roman feet. Though fragmented, a clear pattern displays various different colored slabs. Each large square contains a smaller one of a different hue. An octagon shape is set within that. Inside each octagon, a smaller circle is inlaid in a lighter tint. At the corner of each big square, a four-pointed star forms where the four corners meet.
Judging by the varying thicknesses of the slabs, the researchers deemed them “second-hand“ bits recycled from other structures—with thousands of intricate shapes comprising an overall design of ”very complex geometry.” The researchers noted marble of various qualities and colors.
Small portions of the floor were first seen after a storm in 2012, but due to the difficulty of intervention, direct restoration didn’t begin until May 2024. The floor’s original fragmentation, as well as the action of the seafloor, detached the inlaid slabs from the ocean subfloor.
“This floor, in small portions, had been known for a long time, but the difficult condition of the very fragmented remains had not allowed intervention,” Enrico Gallocchio, from the Archaeological Park of the Phlegraean Fields, told Newsweek. “With an extensive restoration project, it was possible to start working on the most exposed parts, less covered by the sand of the seabed. So, it is not really a new discovery, but understanding its design was a discovery, because we did not know the geometric shape.”
“This discovery tells us about what was going on in [Baiae],” Mr. Gallocchio said, “a very few years before its sinking.”
Famously known as the “Las Vegas” of ancient Rome, Baiae was a resort port, where leisure and moral license were indulged to the fullest. The Stoic philosopher Seneca noted “persons wandering drunk along the beach, the riotous reveling of sailing parties, the lakes a-din with choral song, and all the other ways in which luxury … released from the restraints of law not merely sins, but blazons its sins abroad.” He lamented, “Why must I witness all this?”
In Greek, the name Phlegraean Fields means “burning earth.” They lie within a volcanic caldera formed by the larger Gulf of Naples, near Baiae, and are part of the Campanian volcanic arc, a hotspot for magma activity.
Perhaps Romans of that era knew this. But they probably could not have predicted the eruption of Mount Vesuvius over Pompeii in 79 A.D. and the volcanic activity that caused gradual flooding. Magma pushes up to the surface in a process called bradyseism. This gradually submerged the leisurely Roman resort of Baiae. Ruins of other sunken dwellings and floor mosaics have also been discovered at Baiae.
Looking at the ruins of the villa, researchers believe it collapsed either before or immediately after sinking. They noted that plaster and pieces of architecture from the collapsed walls had fallen onto the marble floor in ways that indicate such a progression.
Divers worked to contain the fragmentation of the slabs. They used special mortar with colors that matched the marble floor. Pieces deemed too scattered or precarious to reintegrate were collected in boxes and brought to the surface to be desalinated in freshwater.
“With these elements, the recomposition of one or more square modules is being attempted, to be consolidated and exhibited in a museum in the future,” park officials stated. Now covered over, the marble floor awaits further restoration in September, though the divers made sure to take plenty of pictures first.
