The world’s most expensive watch ever sold at auction retained that lofty title at a Sotheby’s auction on November 11, which coincided with the 175th anniversary celebration of its maker, Patek Philippe.

The so-called Henry Graves Supercomplication, a pocketwatch made by Patek Philippe in 1933, is the most famous watch in the world and has the distinction of being the most complicated watch ever made completely by human hands. Its reappearance on the auction block, 15 years after it became the most expensive watch ever sold at auction, came in the same year that Patek Philippe commemorates 175 years of making watches. Estimated at more than 15 million Swiss francs (about $15.5 million), the watch sold for $23,983,140 to an anonymous buyer at Sotheby’s Geneva sale of Important Watches. Discussing the sale of the Henry Graves Supercomplication prior to the auction, Tim Bourne, Sotheby’s worldwide head of watches, and Daryn Schnipper, chairman of Sotheby’s watch division, said: “The list of superlatives which can be attached to this icon of the 20th century is truly extraordinary. Indisputably the ‘Holy Grail’ of watches, The Henry Graves Supercomplication combines the Renaissance ideal of the unity of beauty and craftsmanship with the apogee of science. Our offering of this horological work of art in 1999 was unquestionably the highlight of our professional careers and set a world record which has held until today. We are extremely privileged to be offering it once again.”