Archaeologists have discovered a prehistoric burial chamber that is thought to have been constructed around 2,600 years ago.

The preserved wooden burial chamber unexpectedly came to light during excavations near the town of Riedlingen in southwest Germany, on the plains of the Danube, the State Office for Cultural Heritage Baden-Württemberg announced in a press release.

It is located in the center of a large burial mound, that measures more than 210 feet in diameter and stands over 6 feet high today, although it may have once reached around 20 feet high.

"The newly discovered burial chamber represents an extraordinary testimony of our rich monument landscape. 2,600 years after its construction, the [burial chamber] is still fully preserved," Andrea Lindlohr an official with the Baden-Württemberg Ministry for Regional Development and Housing, said at a press conference. "The archaeological heritage of Baden-Württemberg is impressive and opens insights into long-gone periods and societies."

Overview photo of the exposed wooden burial chamber discovered near the town of Riedlingen, Germany. The preserved chamber was found inside a large burial mound. Overview photo of the exposed wooden burial chamber discovered near the town of Riedlingen, Germany. The preserved chamber was found inside a large burial mound. Jörn Heimann/State Office for Monument Preservation in the Stuttgart Regional Council

Celtic peoples who once inhabited southwest Germany constructed so-called "princely burial mounds" such as the one near Riedlingen between around 620 B.C. and 450 B.C.—typically for particularly high-ranking individuals.

Within the burial mound near Riedlingen, archaeologists found the substantial oak timbers of a large, completely preserved burial chamber—with its ceiling, wall and floor—just below the modern ground surface.

According to the State Office, the find is "unique and of outstanding scientific importance" given that buried wood usually does not preserve for very long, usually surviving for a few years to decades under normal conditions.

Timber was the most important building material during the Early Celtic period, but wooden finds from this era are extremely rare.

Only once before has a fully preserved Celtic burial chamber been discovered in Germany—during an excavation near Villingen in the Black Forest in 1890. The remains were not properly documented at the time and only later partially preserved.

The reason that the wooden burial chamber was preserved for so long could be explained by the low oxygen conditions within the mound, experts said.

While analysis of the timbers has yet to be completed, researchers have dated a clublike wooden artifact likely left behind by the Celtic builders after constructing the chamber. This artifact appears to have been made from an oak felled in 585 B.C.—providing, alongside other observations, a possible date for the construction of the chamber.

Schematic graphic reconstruction of the burial mound with the location of the central chamber shown. The chamber is thought to have been constructed around 2,600 years ago. Schematic graphic reconstruction of the burial mound with the location of the central chamber shown. The chamber is thought to have been constructed around 2,600 years ago. State Office for Monument Preservation in the Stuttgart Regional Council/Faber Courtial

"The Riedlingen grave is a stroke of luck for archaeology: the scientific significance of this fully preserved Celtic chamber grave, investigated using modern methods, extends far beyond the boundaries of Baden-Württemberg and southern Germany," Dirk Krausse, an archaeologist with the State Office for Cultural Heritage Baden-Württemberg, said in the press release.

Archaeologists will continue to excavate the site over the next few weeks, with experts hoping that further analysis of the findings will reveal important insights, such as the identify of the individual for whom the burial mound was constructed.

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