Introduced in 2004, the Patek Philippe Gondolo Calendario was the first annual calendar wristwatch to be fitted into a non-round case from the brand. It was also the first Gondolo watch to feature a calendar complication. Inspired by the Art Deco period, the watch features a large tonneau case with eccentric applied Breguet numerals. The calendar windows are trapezoidal-shaped with matching text that arcs across the upper half of the watch. Reference 5135 laid down the foundation for many future annual calendar dial configurations to come from the brand.

The center of the dial features a moon phase and 24 hour indicator to further add to the complexity of the timepiece. A sapphire case back allows for visibility of inhouse Caliber 324/205 which has a power reserve of 45 hours and beats at a frequency of 28,800 beats per hour.