A 7,200-year-old oak-lined water well recently unearthed in eastern Europe may be the world’s oldest known wooden structure—and to keep it from deteriorating further, archaeologists are now scrambling to preserve the vessel in a solution of sugar.

Discovered by construction workers on a strip of Czech motorway in 2018, the oak-based well—newly described in the Journal of Archaeological Science—measures about four and a half feet deep and boasts a square base. Though the structure’s complete history has yet to be unraveled, the team behind the find suspects the well stayed intact because it spent several centuries underwater.

“When blessed by such conditions—wetness and lack of oxygen—oak almost gets fossilized,” study co-author Jaroslav Peška tells Radio Prague International’s Tom McEnchroe. “It becomes very hard and durable.”

To pinpoint the well’s origins, a team led by Michal Rybníček analyzed the annual rings naturally found in tree trunks and their products. In conjunction with radiocarbon dating of some nearby charcoal fragments, this method revealed that the well was likely constructed from oak trees cut down around 5255 B.C.

Though similar wooden structures from around the same time period have been found in other parts of Europe, the newly discovered Czech well is one of the few that’s been dated through tree-ring analysis, giving more exactness to its ancient age, says Penny Bickle, an archaeologist at the University of York who wasn’t involved in the study, to Colin Barras of New Scientist. Because of this, the 7,200-year-old well remains one of the best candidates for the world’s oldest example of wooden architecture.

These numbers place the well and its makers at the end of the Neolithic, a 7,500-year-long period that began about 12,000 years ago. Europe’s first farming populations appeared during the Neolithic, likely spawning the architects responsible for this curious construction feat. Based on the well’s internal structure, which involves four grooved corner posts supporting inserted planks, its creators already had some surprisingly sophisticated “technical know-how,” according to the study.

The well “bears marks of construction techniques used in the Bronze and Iron ages and even the Roman Age,” Peška told Radio Prague International’s Daniela Lazarová last year. “We had no idea that the first farmers, who only had tools made of stone, bones, horns or wood, were able to process the surface of felled trunks with such precision.”

One of the biggest surprises stemmed from the building material rather than the structure’s design. According to New Scientist, several of the corner posts appear to be architectural hand-me-downs, repurposed from another construction project that used trees felled several years prior. Neolithic humans, it seems, were already proponents of sustainability.

What’s more, one of the well’s planks is at least ten years younger than the rest of the structure, suggesting it underwent repairs after a period of heavy use. As Bickle explains to New Scientist, the well’s importance fits in nicely with what’s known of the region, which experienced severe droughts and floods during this time period. The structure may have also played a role in helping early farmers exchange the nomadic lifestyle of hunter-gatherers for a more settled state, allowing them to live off the land year-round.

Researchers from the University of Pardubice’s Faculty of Restoration are hard at work preserving the well’s remains.

“It is by far the oldest object that we will be working on at the faculty, and it will not be an easy task,” says restoration specialist Karol Bayer in a statement. “We cannot let it dry out, or the well would be destroyed.”

To ensure the well’s integrity, the team is slowly immersing its components in a solution of sugar, which has a chemical composition similar to the cellulose found in wood. As the mixture seeps in over the course of the next several years, it will help preserve the structure in its current form. Once frozen, the well will go on display at the Pardubice Museum.