Jean master Mr Jonathan Cheung takes MR PORTER on a tour of the San Francisco lab where the 501 CT was born.

Two thousand years after the Ancient Greek mathematician Archimedes stumbled upon a novel way to determine the purity of gold, his famous cry of “eureka!” would echo throughout the US state of California. The word, which comes from the Greek for “I have found it”, so perfectly articulated the mood of the gold prospectors pouring into the state throughout the late 1840s that it was adopted as the state motto. In 1849 it was incorporated into the Great Seal of the State of California, where it remains to this day.

In the city of San Francisco, once a major port of call on the California gold rush trail, that spirit of discovery lives on in the shape of the Eureka Innovation Lab. This hi-tech facility is where Levi’s tests and develops all of its new denim – and where the brand’s most famous product, the 501, recently underwent its biggest evolution to date.

We visited the lab to meet Mr Jonathan Cheung, senior vice president of design at the 162-year-old brand. A true denim aficionado, the British-born Mr Cheung worked in Italy for several years at Moschino and then Armani Jeans before relocating to San Francisco, via Amsterdam, to join Levi’s. While showing us round the Innovation Lab, he discussed the challenge of improving upon possibly the most iconic piece of clothing in history – and talked us through an exclusive three-piece capsule collection that’s available now, only on MR PORTER.

To find out more, watch the video.