A.Lange & Söhne 1815 Annual Calendar in 18k Rose Gold Box and Papers set ref. 238.032Introduced in 1996 by Patek Philippe, the annual calendar complication has steadily gained popularity. It offers a simpler and more budget friendly option compared to its more complex counterpart, the perpetual. While it can distinguish between months with 30 and 31 days, it still needs to be corrected once a year, specifically at the end of February, as it doesnt account for the shorter month or leap years. At hand, we have a lovely example of this