As celebrity endorsements go, the President of the United States is a pretty good one. But while the Commanders-in-Chief have worn an array of timepieces, only the Rolex Day-Date has earned the nickname the Presidents’ Watch. Introduced in 1956 at the tail end of a hot streak of iconic releases, including the Explorer (1953), the Submariner (1953), and the GMT-Master (1955), the Day-Date was the first calendar wristwatch to include both the date and the day of the week spelled out in full on the dial.

Like its siblings, which were designed to meet the needs of mountaineers, scuba divers, and airline pilots, respectively, the Day-Date was crafted for a specific group of professionals, but in this case, it was ones who wore tailored suits and leather-soled Oxfords to work, not wetsuits and down parkas.

What makes a Day-Date a Day-Date?

Day-Dates have been sold with smooth, fluted, and gem-set bezels, and on Jubilee bracelets and leather straps, but the feature most associated with the watch (and the only one officially bearing its nickname) is its three-link President bracelet. The Day-Date’s association with the Oval Office began in the mid-1960s, when Lyndon B. Johnson was photographed wearing a yellow gold Day-Date in office. LBJ wasn’t the first president to wear a Rolex (Eisenhower had worn a gold Datejust in the ‘50s), nor was he the first to own a Day-Date (JFK was gifted one by Marilyn Monroe), but with a little help from Rolex’s marketing department, the name stuck.

How has the Day-Date changed over the years?

From 1956 to today, the Day-Date’s essential features—a mid-sized precious metal case and a three-hand dial with a day and date display—have remained unchanged. The case has always been 36mm (a relatively large size for the 1950s) with 40 and 41mm versions introduced in the 2000s. Initially offered in 11 languages, the Day-Date’s day-of-week indicator is now available in no fewer than 26, including Basque, Ge’ez, and Cyrillic.

Over the decades, the Day-Date has graced the wrists of Presidents Nixon and Ford, along with countless other powerful dudes, including Jay-Z, Brad Pitt, Tiger Woods, LeBron James, and His Holiness the Dalai Lama (pop off, king). While not as coveted as the Daytona, the Day-Date has achieved some impressive results at auction, most notably $1.3 million for the bejewelled ref. 18059 “Rainbow Khanjar,” one of five such pieces made for Sultan Qaboos of Oman in 1984, which only slightly bested the $1.2 million reference 1803 worn by golf legend Jack Nicklaus.

Wait, so why is the Day-Date such a big deal?

“At this point, the Day-Date is more than just a watch model or collection—it’s an archetype that has guided and shaped watch design and watch culture for 70 years,” says Stephen Pulvirent, the principal of creative agency Rime & Reason. “It’s also a perfect embodiment of what makes Rolex watches so appealing. A bit practical, a bit luxurious, and evolving slowly over time with plenty of quirky and unusual iterations. You could spend your whole life collecting Day-Dates and never get bored.”

Got it. Should I look for a vintage Day-Date or buy a new one?

All vintage Day-Dates are 36mm, with the 40mm model added in 2015, so if you like a bigger watch, your options are limited. The other major difference between vintage and modern Day-Dates is what’s inside. “What has improved is not really the design, it’s more the technology,” says veteran vintage watch dealer Sacha Davidoff.

“The first Day-Dates were slow-set, then single-quick, then double-quick, which are convenient features, because nobody really wants to turn the hands around and around the dial to get the right date.” Then there are the coveted vintage references like the stone-dial “Stella” Day-Dates from the 1970s, he adds, whose distinctive looks are more than worth the inconvenience of manually setting the date.