The wooden remains were first encountered by construction crews in March 2026 at a depth of nearly eight meters (26.2 feet) below ground level. Initially, due to the exceptional condition of the waterlogged oak timbers, researchers from the Bavarian State Office for the Preservation of Monuments (BLfD) believed the structure belonged to the early modern or modern era.
Unexpected Origins Revealed by Tree Rings
The true age of the structure was revealed after samples were analyzed at the BLfD’s dendrochronology laboratory in Thierhaupten. By examining the tree-ring patterns preserved in the oak timbers and comparing them with regional chronologies, scientists determined that the trees had been felled and used for construction during the 4th century BC. This places the building firmly within the Iron Age.
Dr. Stefanie Berg, Head of the Department of Archaeological Heritage Management at the BLfD, highlighted the rarity of the find.
“The combination of the exceptional location on the banks of the Main River, the outstanding state of preservation, the hitherto unique timber-and-stone construction, and the Iron Age dating makes this find unique,” she stated.
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A Unique Timber and Stone Construction
The structure’s sophisticated design features large oak beams finished with a dry-stone wall facing the river. Such masonry is highly unusual for this era. “Stone masonry is extremely rare for the Iron Age,” Berg explained. “When stone structures from this period are documented, they are usually components of fortified structures, such as post-and-beam walls.”
View into the excavation pit, with the present-day course of the Main River visible on the right. (BLfD)
This unusual combination has led experts to theorize that the building may have been a significant riverside settlement, an elite structure, or possibly a Celtic harbor. Its position beside the Main River indicates that the waterway likely played a crucial role in the community's trade, transport, and economy.
Uncovering an Ancient Settlement
For years, researchers have suspected that a significant Iron Age central settlement existed in the area of modern-day Aschaffenburg Old Town, based on isolated finds like a gold finger ring and an animal-head fibula. However, little was known about its layout. The newly discovered riverside structure provides the clearest physical evidence yet for a larger settlement center in the region.
3D image of the complete archaeological feature. (BLfD)
Excavation work continues under challenging conditions inside a construction pit reaching depths of up to ten meters. Archaeologists are working closely with engineers to balance the scientific investigation with ongoing construction and strict safety requirements. Detailed 3D models of the site have been created, and researchers hope further analysis will reveal the true purpose of the building and offer new insights into the development of the Bavaria region during the Iron Age.
Top image: Cross-section of the entire structure. On the right is the wall front facing the Main River, while in the foreground are the preserved timbers, nearly 2,400 years old. Source: BLfD
By Gary Manners
References
BLfD. 2026. Eisenzeitliches Bauwerk lässt Forschende staunen. Bayerisches Landesamt für Denkmalpflege. Available at: https://www.blfd.bayern.de/mam/blfd/presse/pressemitteilung_++_eisenzeitliches_bauwerk_l%C3%A4sst_forschende_staunen_++_blfd.pdf
Carvajal, G. 2026. A Possible Iron Age Celtic Harbor Found on the Bank of the Main River in Germany. La Brújula Verde. Available at: https://www.labrujulaverde.com/en/2026/05/a-possible-iron-age-celtic-harbor-found-on-the-bank-of-the-main-river-in-germany/
Radley, D. 2026. 2,300-year-old Iron Age riverside structure discovered beneath German city. Archaeology Magazine. Available at: https://archaeologymag.com/2026/05/iron-age-structure-discovered-beneath-german-city/
