Drought Reveals Hidden Roman Ruins in Switzerland After Nearly 2,000 Years

Archaeologists in Switzerland have discovered previously hidden traces of an ancient Roman city after unusually dry weather caused vegetation above buried structures to change in appearance.

The discoveries were made around Avenches, the site of Aventicum, which was the capital of Roman Helvetia around 2,000 years ago. Archaeologists used drone images to document patterns that appeared in fields during the country’s exceptionally hot summer.

Ancient Buildings Appear From Above

The aerial images revealed outlines of Roman structures that had previously been unknown or poorly understood. Among the discoveries were traces of thermal baths, houses, roads and a possible temple.

The unusual patterns are known as “parch marks.” They can appear when vegetation growing above buried walls or other archaeological remains dries out at a different rate from surrounding plants.

Daily Drone Images Helped Map the Site

After a local history enthusiast alerted archaeologists to unusual patterns in the fields, researchers in the Swiss canton of Vaud began taking daily drone photographs of the area.

The team then compared the new aerial images with existing archaeological maps. The discoveries filled previously blank areas and helped researchers correct some earlier assumptions about the ancient city.

A Rare Look at Roman Aventicum

Aventicum was an important Roman settlement that developed in what is now Switzerland. Although much of the ancient city remains underground, archaeological work has gradually revealed its streets, buildings and public spaces.

Jordan Anastassov, an archaeologist for the canton of Vaud, described the latest discoveries as among the richest findings at the site in decades. :contentReference

Modern Weather Reveals Ancient History

The discovery shows how changes in the modern environment can sometimes provide unexpected clues about the past. In this case, dry conditions exposed patterns that would normally remain difficult to see from ground level.

Archaeologists are now using the new information to expand and refine their understanding of Aventicum without having to excavate every newly identified structure.

Sources

• Reuters — “Swiss archaeologists redraw Roman maps after drought discoveries” — September 29, 2026.
• Reuters — Reporting from Avenches, Switzerland, on newly identified Roman structures revealed by drought-related vegetation patterns.