Production of this reference started in 1993. It is the second most complicated wristwatch ever produced by Patek Philippe and takes its place in a long tradition of extremely fine and highly complicated mechanical timepieces. It is surpassed only by Ref. 5002 the ?Sky Moon Tourbillon?. Ref. 5016 incorporates a perpetual calendar with a retrograde or flyback date hand whose specially developed mechanism absorbs almost no energy when the hand returns on the 1st of each month. Month year and leap year indications will change instantaneously and if it is always kept running no adjustments need to be made to the watch until Feb. 28th 2100. (The moon phase indication will show a deviation of one single day only after 122 years and 45 days). The minute repeater sounds with unequalled purity and clarity and the tourbillon cage lies on the same rotational axis as the balance and fourth wheels a very difficult configuration. All harmoniously blended together in this timepiece of the highest quality beauty and prestige.