One of Audemars Piguet’s most historic timepieces just sold for a record sum at auction—and the buyer will come as no surprise.

The most-complicated AP pocket watch still in private hands hammered down for $7.7 million at Sotheby’s New York yesterday, making it the most expensive timepiece from the brand ever to go under the gavel. And, during a 10-minute bidding skirmish between four collectors, Audemars Piguet itself ended up reclaiming its S. Smith & Son Astronomical Watch, nicknamed “Grosse Pièce” (or “Big Piece” in English), as it announced in a press release after the sale.

The ultra-rare watch far surpassed its top estimate of $1 million, and it’s easy to see why. “Grosse Pièce,” or No. 16869, is the most comprehensive astronomical timepiece ever brought to life by the Swiss watchmaker. Done up in 18-karat yellow gold, the bonkers creation shows London’s night sky, complete with 315 stars and 18 constellations—the only watch from the brand to have such a celestial chart, according to Audemars Piguet’s Heritage Department. That extraordinary feature is paired with a sidereal time display, a perpetual calendar, moon phases, and the equation of time display, as well as a minute repeater, grande and petite sonnerie functions, a chronograph, and AP’s only tourbillon in a pocket watch from this era.

In total, with 19 complications, the Big Piece shares the title of Audemars Piguet’s most complicated pocket watch with the “Universelle” timepiece from 1899. And thanks to the remarkable combination of all those complications, the sky chart, and the tourbillon, the Grosse Pièce” has cemented itself in the history of haute horologerie.

As for its backstory, Smith & Sons of London commissioned the “Grosse Pièce” back in 1914 on behalf of an American client. After six years of crafting, the customer received the timepiece in 1921. Upon its delivery, the pocket watch essentially disappeared from public eyes for decade, only adding to its illustrious tale; the only traces of its existence could be found in archival notes and rare photos. Then, famed watch collector Robert M. Olmsted added the Big Piece to his prestigious lineup in 1970. And now, of course, the watch has been thrust back into the limelight, courtesy of Sotheby’s auction of the watch treasure trove belonging to Olmsted, in a sale called Exceptional Discoveries: The Olmsted Complications Collection. 

Now that the “Grosse Pièce” is back in the hands of AP, the watchmaker plans to take the rarity on a multi-year world tour, with stops at select retailers and events. Eventually, the pocket watch will reside at the brand’s Musée Atelier Audemars Piguet in Le Brassus, where it will join its pal “Universelle.” That’s a fitting ending for such a grand piece of horological history if we’ve ever seen one.