Drought Reveals Hidden Roman Ruins in Switzerland, Helping Archaeologists Redraw an Ancient City

An unusually hot and dry summer in Switzerland has helped archaeologists uncover traces of a Roman city that had remained hidden beneath fields for centuries.

The discoveries were made around Aventicum, the former capital of Roman Helvetia, near the modern town of Avenches in the canton of Vaud. Archaeologists used drones to photograph the landscape every day between June and August after a local history enthusiast alerted them to unusual marks appearing in fields.

Plants Revealed What Was Hidden Underground

The clues appeared as so-called “parch marks.” When vegetation grows above buried walls, roads or other structures, the plants can wither differently from those growing over normal soil. During periods of drought, these differences can become clearly visible from above.

Drone images revealed traces of previously unknown or poorly understood structures, including thermal baths, houses, roads and what may have been a temple.

Several of the discoveries were located in areas of Aventicum that archaeologists had never excavated. Researchers then placed the new findings onto existing maps, filling gaps and correcting some earlier interpretations of the ancient city.

One of the Richest Discoveries in Decades

Jordan Anastassov, an archaeologist working for the canton of Vaud, described the discoveries as among the richest made at the site over the past two generations of archaeologists.

Some of the marks disappeared after fields were mowed and temperatures dropped. However, the outline of a previously unknown pool connected to the Roman baths remained visible in a field where the vegetation was still affected by the unusually warm conditions.

A New Look at Roman Life

Aventicum was an important Roman city that flourished around 2,000 years ago. At its height, the settlement was home to a large population and contained public buildings, roads and bathing complexes.

The newly revealed structures could help researchers understand how the city was organized and how its residents lived. Archaeologists plan to present their findings to other experts and may carry out targeted excavations in the future.

The researchers do not want droughts to become a normal way of discovering archaeological sites, but they are using the rare opportunity to learn more about a city whose buried remains are still revealing new secrets.

Sources

• Reuters — “Swiss archaeologists redraw Roman maps after drought discoveries” — September 29, 2026.
• Jura & Trois-Lacs Tourism — “Aventicum, its site and its thermal baths” — 2026.