Like the Fender Stratocaster and the Porsche 911, the Rolex Datejust was so elegantly conceived and executed during the mid-20th Century that it has remained in production to this day, more or less in its original form. And like the Strat and the 911, the Datejust has undergone development as new ideas, materials, and technologies emerged, but the basic design has been remarkably stable. These companies knew not to mess too much with a classic.
And, yes, the notion that the Rolex Datejust is the Strat or the 911 of watches is exactly the point. The Datejust has been a brand icon for Rolex ever since it came out in 1945, and today — just like the Strat and 911 — the Datejust looks so current, so fresh that it’s easy to forget that these watches were initially designed over 70 years ago.
1945–1953: Rolex 4xxx Series Datejust

Since the 1920s, decades before the Datejust, Rolex had been successfully selling their Oyster Perpetual watches; “Oyster” because the watches were watertight like an oyster, and “Perpetual” because they automatically wound themselves, thus seeming to run perpetually.
To celebrate the firm’s 40th Anniversary in 1945, Rolex produced reference 4467, an Oyster Perpetual with a date complication, and they called it The Datejust. The Datejust was the very first waterproof, automatic wristwatch to incorporate a date window, and this mechanism changed dates very close to midnight (unlike many date complications which take hours to change over).