The legendary Holy Grail, said to have been used by Jesus during the Last Supper to transform wine into his blood during the first Eucharist, has captivated the imagination of treasure hunters for centuries. Though we may never know if this holy relic ever existed, one tantalizing theory holds that it lies hidden beneath the foundations of a remote chapel built by the Knights Templar in western Poland.

“The legend says that Templars, under cover of darkness, sunk a wooden box with golden coins and the Holy Grail,” Marek Karolczak, a local historian, told CNN Travel. The lake mentioned in the stories dried out long ago, “and the treasure has either been stolen or lost forever in the swamp,” he added.

Now, archaeologists are investigating one of the chapels the order built in western Poland upon its return from the Holy Land. The small village of Chwarszczany, in the region of West Pomeranian, is home to the chapel of St. Stanislaus, constructed from red bricks by the Templars as both a place of worship and a defensive fortification in 1232.

According to recent investigations, the chapel also serves as the final resting place of several Knights Templar, and appears to conceal a hidden passageway leading to an underground chamber.

The St. Stanislaus chapel in Chwarszczany was built by the Knights Templar. Could they have hidden the Holy Grail in the secret tunnel below its foundations? Photo by Cezarde62, Wikimedia Commons.

“Our GPR [ground-penetrating radar] has detected gothic crypts with the remnants of Templar knights beneath the chapel,” local archaeologist Przemysław Kołosowski told CNN. “According to legends and medieval documents, there was a well in the vicinity of the chapel. Rumor has it that the well served as an entrance to a secret tunnel. This still requires an exhaustive archeological investigation.”

Adding to the intrigue, a secret underground tunnel also runs beneath the nearby town of Myślibórz. Just a four hour ride from Chwarszczany by horse—half hour by car—the town was settled by the Templars in 1238. Could archaeologists be on the verge of discovering a cache of Templar treasure, or perhaps the Holy Grail itself? Time, and careful excavation, will tell.

The St. Stanislaus chapel in Chwarszczany was built by the Knights Templar. Could they have hidden the Holy Grail in the secret tunnel below its foundations? Photo by Piotr Grzegorz, Wikimedia Commons.

The powerful Catholic military order, founded in 1139 to protect pilgrims in the Holy Land, travelled throughout Europe and the Middle East during the Middle Ages.

Pope Clement V disbanded the Templars in 1312, after King Philip IV of France arrested many members of the order and tortured them into giving false confessions of sacrilege and homosexuality.

Shrouded in secrecy with shadowy rituals, the Templars have long fueled conspiracy theories that they recovered the Holy Grail during the Crusades and became its guardian.