The mechanical watch is often overlooked as an icon of 20th century design but this week in Milan the balance is somewhat redressed, as one of the greatest watch designs of all time - the Audemars Piguet Royal Oak - is celebrated in an eponymous exhibition at the Milan Triennale.

The watch was created by the late Gérald Genta in 1972. Back then, watch creatives were called 'stylists'  rather than designers, and Genta was - and always will be - one of the most highly regarded stylists in the profession. So much so, that when his boss at AP was pressed by Italian buyers to deliver them 'a sports watch with a more modern image, that they could wear at the wheel of their car, on the deck of a boat but also at a disco', Genta was set the task of designing it in just one night.

And so the world's first luxury sports watch was created, on a scrap of paper, in just under 24 hours on the eve of the 1972 Basel watch fair. It was a risky move, because Genta designed it in steel rather than gold but with a heftier price tag. Yet the understated utilitarian design - inspired by Genta's recollection of a diver's helmet he'd seen as a child, bolted together with giant nuts - was so revolutionary, everyone who could afford it wanted one before everyone else. Genta had created a seriously desirable product that made the world look at watch design in a new light.

The story of the watch and all those who had a hand in its design is played out in the exhibition, which started in New York last month and will travel to Paris, Beijing and Singapore throughout the year. Artists, including the installation artist Sébastien Léon Agneessens, have also contributed works, underlining the creative vision that enables a great design to get off the page and become a reality.  A new book, 'Royal Oak', also launched as part of the celebrations.