Archaeologists have just finished a thorough study of the Roman Imperial Baths (Kaiserthermen) under Baden-Baden’s marketplace in Germany. This marks the first such examination in more than 180 years. Experts from ArchaeoConnect and the State Office for Monument Preservation (LAD) led this dig. Their work has shed new light on the structure and preservation of this ancient bathing complex, which dates back to the late 1st century CE.

View of the ancient walls and bricks of the Roman underfloor heating, above modern fillings and a concrete slab. Credit: LAD, Sarah Roth

The Roman baths were known in antiquity as Aurelia Aquensis (“Aurelia-of-the-Waters”) after Emperor Marcus Aurelius Severus Alexander Augustus. These baths were among the biggest bathing spots in Baden-Württemberg. The builders put them right on top of the H๏τ springs of Florentinerberg. This was the first known use of geothermal waters in the region.

Archaeologists first discovered parts of the site in the mid-19th century, but research has been limited since that time. Recently, sewer renovations gave experts a chance to study a 50-square-meter section of the baths using modern techniques.

View of the ancient walls and bricks of the Roman underfloor heating, above modern fillings and a concrete slab. Credit: LAD, Sarah Roth

Sarah Roth, an archaeologist from LAD, said: “In 2024, the necessary replacement of water pipes in the market square area made it possible for the first time to gain archaeological insights on a meaningful scale in the area of the Imperial Baths.”

Canal and pipework over the last few decades have caused considerable damage to the Roman building structure (front of the image). Credit: LAD, Sarah Roth

The dig unearthed Roman-era walls just one meter under the current ground level, with some walls not documented in earlier research. Archaeologists also found hypocaust bricks used in ancient underfloor heating setups, confirming that parts of the complex were heated. In the part where the biggest known room of the baths once stood, the team identified multiple layers of screed, which once held up marble cladding on the walls and floors. What’s more, they found three well-preserved steps leading into a bathing pool, giving us a direct link to the experiences of bathers almost 2,000 years ago.

The new investigation revealed the baths’ structure, but it also showed how much damage later building projects caused. “The construction of a branched tunnel system in the late 19th century and the laying of canals and pipes in recent decades repeatedly damaged and reduced the structural substance of the Baths under the marketplace,” Roth explained.

Remnants of bathing luxury: Parтιтion wall with screed layers (left in the image), a section of the marble cladding at the floor-wall junction, and a rounded corner of the bathing pool with steps. The pipe and the filling above are modern. Credit: LAD, Sarah Roth

Even with these challenges, the study stands as the most extensive examination of the site in more than 50 years. It’s also the first to use modern archaeological documentation methods. “Some areas were uncovered for the first time since 1849 under archaeological supervision,” Roth added. “Until now, the preservation state of the ruins at this site was entirely unknown.”

Since 2021, UNESCO has listed this place as a World Heritage site, underscoring its cultural and archaeological importance.

More information: LAD / ArchaeoConnect