In 2023, the licensed detectorist Constantin Fried discovered a miniaturized Roman lock during a survey of a field near Petershagen-Frille in the Minden-Lübbecke district. Recognizing its significant nature, Fried reported the find immediately after making it to LWL-Archeologie für Westfalen in Bielefeld.

This gold and iron box lock measures only 1.1 cm x 1.2 cm. Credit: LWL /S. Brentführer

Experts confirmed that the piece he had found was a miniature example of a Roman cylindrical lock, the kind usually used for fastening chests and containers. This lock, which measures just 1.2 by 1.1 centimeters, is smaller than a one-euro coin and is considered a unique find in Europe. Fried said: “I could hardly believe it myself when I held the find in my hand. Roman locks like these are typically much larger and made of iron or bronze components.”

Dr. Barbara Rüschoff-Parzinger, cultural director at LWL and an archaeologist, explained, “The lock was certainly manufactured in the provincial Roman territory and can be dated to the 3rd or 4th century CE based on its shape, technical design, and decorative style.” The researchers think it is quite likely that this object might have come over to Westphalia as war loot, by trade, or as a relic acquired as a souvenir from a soldier who returned from service in the Roman army.

The lock consists of two cylindrical plates, the top and the bottom being sealed, and secured with three gold rivets. Its outer casing is finely adorned with sculpted perforations, attesting to a quality product. The original key and chain are missing, and only a single chain link is still attached to the lock.

The replica of the lock, made of brᴀss and steel on a scale of 4:1 (reconstruction: LWL-/Eugen Müsch). Credit: LWL/Stefan Brentführer

To analyze the lock’s internal mechanism, researchers turned to advanced imaging technologies. Traditional X-ray scans proved ineffective due to the density of the gold casing, leading the team to employ 3D neutron computed tomography (CT). This method, conducted by Dr. David Mannes and Dr. Eberhard Lehmann from the Paul Scherrer Insтιтute in Switzerland, provided a clear view of the iron mechanism inside. The scans revealed a frame with a spring, a guide rail, a bolt, a base plate, and a pin.

Though damaged, experts were able to reconstruct the lock mechanism. A complete working replica, four times the size of the original, was created by an LWL archaeological restorer based on comparative finds and imaging material. “With the remaining chain link still attached, we were also able to reconstruct a chain for the lock, which must have had at least six links to function properly,” said Dr. Michael Rind, Director of LWL Archaeology.

The 4:1 scale reconstruction of the lock with chain (reconstruction: LWL /Eugen Müsch). Credit: LWL /Stefan Brentführer

Besides its technical significance, the lock exemplifies the interactions among local elites in Westphalia and the Roman Empire. Further questions remain open to research: Was this a unique commissioned piece, or do other undiscovered examples of such locks exist?

More information: Landschaftsverband Westfalen-Lippe (LWL)