Maen Huail sits in St Peter’s Square at the center of the Welsh town of Ruthin. This weather-beaten stone, just under four feet long and two feet tall, is believed to be the place where King Arthur of the Britons beheaded Huail.

The legend, first recorded in the mid-16th century, tells that Huail, brother of famed historian Gildas was warring with Arthur over a paramour. Though they ultimately made peace with each other, Huail first wounded Arthur with a strike to the king’s knee.

As part of their truce, Arthur forbid Huail from ever mentioning the injury and they parted ways. Some time passed when, while dancing among his court, King Arthur overheard a familiar voice remarking, ‘This dancing was all right if it were not for the knee.” Knowing that his old foe had broken their oath, Arthur commanded Huail to show his face. On their reunion, the king executed Huail upon the stone that is now known as Maen Huail.

Though this legend postdates the event it details by almost 1,000 years, and the stone itself was first recorded 150 years later, the difference may be the result of Huail’s brother, Gildas the Wise. Outraged at the murder of his brother Gildas, a popular historian of his time, cast into the sea all his works detailing Arthur’s life and reign.