stronomical watches are deeply rooted in the history of the Vallée de Joux, where watchmakers have always drawn their inspiration from the clear night sky. Audemars Piguet’s expertise in astronomical complications dates back to the founders’ school watches, both completed around 1875.

Audemars Piguet’s first complete calendar wristwatch was put into production in 1921 and sold three years later to the renowned retailer Gübelin. From 1921 to 1970, 188 complete calendar wristwatches were produced – a small part of the Manufacture’s total production during these years.

In 1955 the company released the world’s first perpetual calendar wristwatch with leap year indication, nine examples of which were created between 1955 and 1957.

The Royal Oak Perpetual Calendar 25554 illustrated the cover page of an article published in Europa Star in 1984 on the Swiss watch industry and the revival of calendar watches.

© Europa Star

The brand broke another record in 1978 at the height of the quartz crisis with the world’s thinnest self-winding perpetual calendar wristwatch of its time, Calibre 2120/2800. Conceived in secret by three watchmakers, this ground breaking perpetual calendar movement achieved its extra-thinness (3.95mm) by using the ultra-thin Calibre 2120 (2.45mm thick), launched in 1967, as its base. Over the next 18 years, more than 7,000 movements were produced, cased and sold, ushering in a new era of growth for the brand and paving the way for the revival of classic complications.

In 1984 this calibre powered the first Royal Oak Perpetual Calendar (39mm in diameter), Model 5554, soon followed by other references in the collection.

Haute Joaillerie Royal Oak Perpetual Calendar Openworked 25659BA, N° 03, dial side. Perpetual Calendar: day, date, month, phase and age of the Moon. Extra-thin (3.95mm) and openworked self-winding Calibre 2120/2800, movement 274089. Bracelet 344. 39mm case C31040 in 18k yellow gold entirely set with brilliant-cut diamonds. Sold on December 15, 1988. Sold at auction by Phillips in Geneva on May 6, 2022, lot 72.

Photo: ©Phillips

Launched in 2015, Calibre 5134 adapted the perpetual calendar movement to a larger 41mm case diameter, while maintaining a thin profile of 4.3mm. It was first housed in a new Royal Oak model with a dynamic aesthetic, bringing renewed attention to this classic complication, which had been in decline since the end of the twentieth century.

This revival was confirmed in 2017 with the release of the Royal Oak Perpetual Calendar 26579CE in black ceramic, which caused a sensation. This calibre powered numerous perpetual calendar wristwatches across the Manufacture’s collection until 2024, when it was retired.. It was last featured on the Royal Oak Perpetual Calendar “John Mayer” Limited Edition, bringing down the curtain on a story that began in 1978.

Royal Oak Perpetual Calendar 25932BC. Perpetual calendar: day, date, week, month, leap year, phase and age of the Moon. Self-winding Calibre 2141/2806, Movement 442916. Bracelet 789. 33mm case D80708 in white gold set with 540 diamonds. Sold in Germany in May 1999.

In 2018 the Manufacture opened yet another chapter in its history of perpetual calendar timepieces with the launch of the revolutionary 41mm Royal Oak Selfwinding Perpetual Calendar Ultra-Thin, known as RD#2 – the world’s thinnest self-winding perpetual calendar wristwatch of its time. This 6.3mm-thick watch houses Calibre 5133, an ultra-thin movement measuring just 2.89mm in height, which was fully redesigned to incorporate all the perpetual calendar functions on one single level, heralding a new generation of astronomical watches.

Building on the patented inventions that made RD#2 possible, Calibre 7138 pushes the limits of feasibility once more by offering an intuitive, user-friendly complication that can be set and corrected anywhere, without tools. An ergonomic complication that opens up new horizons for Audemars Piguet in terms of both technology and aesthetics.

1982-1996. Calibre 2120/2800SQ, bridge-side view. Thinnest openworked self-winding perpetual calendar of its era (3.95mm): day, date, month, Moon phases. Movement 324301, produced in 1991.