The Royal Oak is a timepiece that set the benchmark on many fronts. Not only was it the very first luxury sports watch when launched in 1972, it was also the very first luxury sports watch featuring a complication. In 1982, exactly 10 years after its launch, the Royal Oak was presented with a perpetual calendar. Interestingly, the birth of the Royal Oak Perpetual Calendar is the result of research undertaken by three brilliant watchmakers wishing to create an extra slim perpetual calendar mechanism built upon caliber 2120, which cased other iconic models such as Patek Philippe's Nautilus, Vacheron Constantin's 222 and the Royal Oak itself. Caliber 2120/2800 was born in 1977 making it the world’s slimmest perpetual calendar movement with a thickness of only 3.95mm. The subsequent years were used in finalizing the development and finally in 1982 the Royal Oak took the horological world by surprise, once again, with the launch of a model with perpetual calendar. #25820 #25654 #watchporn #audemarspiguet