A year ago, at England’s Blenheim Palace, officials discovered a priceless piece of history hiding in plain sight when an antiques expert identified a marble flower planter—used to grow tulips in a palace garden—as part of a Roman sarcophagus. The relic was cleaned and restored, and recently put on public display inside the house, The New York Times reports.

Located in Oxfordshire, England, Blenheim Palace is the main residence of the Dukes of Marlborough. It’s one of England’s largest houses, and was named a UNESCO World Heritage Site in 1987. As for the Roman sarcophagus, it came to Blenheim Palace sometime during the 19th century. Originally, the marble relic was used to collect water from a local spring; in later years—as early as the 20th century—it was integrated into a rock garden. There the sarcophagus sat for decades, attached to a lead cistern, until last year, when a visiting antiques specialist happened to notice it while walking through the garden.

The 6-foot-long sarcophagus fragment was once the front of a coffin, and is missing its base, sides, and back. It’s believed to date back to the 2nd century CE, and features carvings of lion heads and Roman gods, including Hercules, Ariadne, and a tipsy Dionysus leaning on a satyr. Experts don’t know whether anyone was actually buried in the sarcophagus, but thanks to its fine carving, they believe it belonged to someone of high social status.

The sarcophagus is likely valuable: It has some wear and tear, but it's mostly in good condition. Similar artifacts of lesser quality have been auctioned off for as much as $121,000. But despite its potential worth, officials at Blenheim Palace say they have no interest in selling the piece.

Blenheim Palace isn’t the only household to own a Roman sarcophagus unawares, or use it as a planter. In 2012, a Roman marble coffin—used as a flower trough by homeowners in Dorset, England—was sold at auction for $133,000. And after reading about the discovery, a retired couple in Newcastle, in northeast England, realized a marble planter in their own gardens was also a Roman sarcophagus, dating back to the 1st or 2nd century CE. They sold it in 2013 for $55,400.

[h/t The New York Times]