A vast Roman wall mosaic hidden beneath the Baths of Trajan for nearly 2,000 years is opening to the public, giving visitors a rare look at one of the largest surviving decorative complexes from ancient Rome.
The first-century A.D. “Great Mosaic” stands alongside an ancient fresco known as “The Painted City.” Archaeologists uncovered the artworks in underground spaces on Oppian Hill, near the Colosseum, during excavations that began in the 1990s.
The discovery adds to a series of remarkable finds beneath the Italian capital. Archaeologists recently uncovered a hidden Roman complex with rare mosaics beneath Rome’s Villa Celimontana, also near the Colosseum.
Years of excavation and restoration followed at the Great Mosaic site. Archaeologists are still working there and have not yet found the full extent of the mosaic.
Archaeologists search for mosaic’s edge
The Great Mosaic rises about 15 meters, or 49 feet, and extends across four levels of decoration. It features life-size figures, columns and theatrical scenes. Blue and white tiles survive alongside traces of decorative materials that once reflected light across the surface. Archaeologist Francesco Pacetti said its true size remains unknown. “We think it’s the biggest wall mosaic ever found in the Roman world, and we are still digging to find where it stops,” Pacetti said.
Elaborate mosaics were important features of wealthy Roman properties. Another ancient Roman home uncovered near the Colosseum contained an extraordinary mosaic made from shells, marble and precious glass. Researchers believe the newly opened decorated spaces may also have formed part of an elite private residence. They are investigating possible connections to Emperor Nero’s Domus Aurea, the vast palace complex built after the Great Fire of Rome in A.D. 64.
Ancient city remains a mystery
Nearby, “The Painted City” offers a different view of Roman life. The roughly 10-square-meter fresco shows a fortified city from above. Its detailed urban landscape includes a theater, temple, public squares, statues, and residential neighborhoods. Researchers have not identified the city. “It could be a real place or an idealized city, we are not sure,” Pacetti said.
A massive 2,000-year-old Roman mosaic is finally open to the public beneath the Baths of Trajan in Rome.
Archaeologists believe it may be the largest wall mosaic ever found in the Roman world and they still haven’t found where it ends. pic.twitter.com/Li7f5cTR5Y
— Tom Marvolo Riddle (@tom_riddle2025) September 9, 2026
Rome’s cultural superintendent, Claudio Parisi Presicce, said that if the fresco represents a real location, the city must have been “extremely important.”
Artworks survived beneath Trajan’s baths
The decorated structures predate the Baths of Trajan, which Emperor Trajan dedicated in A.D. 109. The enormous public complex covered about 15 acres and incorporated earlier structures in the area.
The baths are among the major projects associated with Trajan’s transformation of imperial Rome. A previous discovery has explored how the Greek-Syrian architect Apollodorus of Damascus helped shape some of Trajan’s greatest monuments, including the expansive Baths of Trajan. Those changes left the earlier artworks hidden beneath Rome for centuries.
Visitors allowed underground
Rome officials have decided to open the site even as archaeological work continues. “It was important not to wait any longer to open it to the public,” Mayor Roberto Gualtieri said. The opening follows other efforts to make previously inaccessible parts of ancient Rome available to visitors. In 2025, the Colosseum’s hidden imperial passage opened to the public after extensive restoration.
Access to the Great Mosaic will initially be limited to groups of no more than 15 visitors. Conservation experts will monitor humidity and other environmental changes inside the underground gallery before officials consider allowing larger groups.
Meanwhile, excavations will continue. With archaeologists still searching for the Great Mosaic’s edge, more of the ancient masterpiece may remain hidden beneath Rome.
See all the latest news from Greece and the world at Greekreporter.com. Contact our newsroom to report an update or send your story, photos and videos. Follow GR on Google News and subscribe here to our daily email!
