Audemars Piguet Royal Oak Perpetual Calendar Steel — Silver Grande Tapisserie Dial | Ref. 26574ST.OO.1220ST.01

To marry the perpetual calendar complication with Gerald Genta's 1972 Royal Oak design is to unite two of horology's most demanding achievements in a single 41 mm stainless steel case just 9.5 mm thick. Ref. 26574ST.OO.1220ST.01 accomplishes this through Calibre 5134, an in-house perpetual calendar movement that programmes the Gregorian calendar's irregularities—including leap years—mechanically into its gear train, requiring no manual correction until the year 2100. The date, day, month, week number, astronomical moon phase, and leap year indicator are all displayed on the silver-toned dial, arranged with the spatial clarity that only a manufacture with decades of perpetual calendar experience can achieve.

That dial is finished with AP's hallmark Grande Tapisserie relief pattern—an interlocking grid of raised squares that catches light differently at every angle, bringing the otherwise complex information display to life. White gold applied hour markers and Royal Oak hands with luminescent coating ensure legibility, while the glareproof sapphire crystal eliminates reflections in any lighting condition. A matching sapphire caseback reveals the movement's meticulous finishing, with alternating côtes de Genève stripes and bevelled bridges.

The integrated stainless steel bracelet—itself a feat of multi-link engineering that flows without interruption from the case—closes with the AP folding buckle. Water resistant to 20 metres, this perpetual calendar is positioned as both a wearable complications masterclass and a steel sports watch of the highest order. For the serious collector, an integrated-bracelet perpetual calendar in the Royal Oak idiom represents one of the most coveted horological propositions in current production.