This Patek Philippe 3448 is one of the true landmarks of twentieth-century watchmaking, the first serially produced automatic perpetual calendar wristwatch made by Patek or by any maker, and a reference any serious collection of complicated Patek aspires to hold. It is powered by the celebrated automatic calibre 27-460 Q, a perpetual calendar with moonphase descended from the movement of the reference 2526 and long regarded as one of the finest self-winding calibres ever built, with its free-sprung Gyromax balance and full solid-gold rotor. The 18K yellow gold case measures 37.2mm across and just 11.5mm in thickness, its wide, gently sloping bezel giving the flat, disc-like profile that collectors named Disco Volante, the flying saucer. The dial is silvered. Produced across the longest run of any Patek perpetual calendar and spoken of in the same breath as the 1518 and 2499, it stands among the most historically significant wristwatches the firm has ever made.