The Patek Philippe references 5035 and 5036 occupy a landmark position in modern horology as the watches that introduced the Annual Calendar complication to the world. Unveiled in 1996, the reference 5035 presented an entirely new complication that automatically distinguished between 30 and 31-day months, requiring adjustment only once each year at the end of February. This ingenious innovation bridged the gap between a simple complete calendar and the far more complex perpetual calendar, providing collectors with a highly practical complication that combined everyday usability with exceptional mechanical sophistication. Powered by the automatic Calibre 315 S QA, the 5035 featured an elegant round case, asymmetrical dial layout and a clean, legible display that immediately established the design language for an entirely new family of Patek Philippe complications. Shortly afterwards, the reference 5036 expanded the concept by introducing an integrated bracelet version, offering the same revolutionary complication in a more contemporary and luxurious execution while preserving the movement and overall dial architecture of the original.

The significance of the 5035 and 5036 extends far beyond their individual designs, as they laid the foundations for one of Patek Philippe's most successful and influential complication families. Every subsequent Annual Calendar reference—including the 5125, 5135, 5146, 5147, 5205, 5235, 5326 and 5396—can trace its origins directly to the innovation introduced by these pioneering models. The Annual Calendar remains one of Patek Philippe's most celebrated inventions, demonstrating the manufacture's ability to solve practical horological challenges through elegant engineering rather than unnecessary complexity. Today, the references 5035 and 5036 are regarded as milestone watches in the history of modern watchmaking, admired not only for introducing an entirely new category of complication but also for establishing a legacy that continues to define Patek Philippe's contemporary collection.