Like the park, the industry has moved up to the cloud, where the air is thinner: there is less stuff, more talk. Where once the tech industry largely concentrated on devices and software, far more firms now make money out of interactions between users and with online services. The newer firms are less often in the Valley than in San Francisco itself, and specifically in the vicinity of Salesforce Park, a part of town that was previously home to boarded-up warehouses from sunset industries. Now, 15 years on, I tend to roam in a completely different area to cover the tech industry. In those days, before Wi-Fi became widespread, people still talked to each other in coffee shops. This was ground zero for the dotcom boom, the era of the browser wars, when casual still meant casual, and Palm Pilots and BlackBerries were the hot new handheld devices. When I covered technology for The Economist in the late 1990s and early 2000s, I often hung out on University Avenue in Palo Alto, about an hour’s drive south of San Francisco. Most obvious among the new generation is Salesforce, a software giant that pays $4m each year to name the transit centre that I am currently exercising on top of – and which also occupies the region’s tallest building. As I struggle to balance on one leg, I can see Box, Databricks, Okta and Slack, all of which help people to communicate or do clever things with their data that they had no reason to do a decade or so ago. Many of the surrounding towers house private companies known as “unicorns” – meaning that they’re valued at more than $1bn – most of which offer some kind of online business service. This recently opened green space is connected with another cloud too: the computing kind. It is four floors above street level and six city-blocks long, all encircled by office towers with glass façades that are reflecting the blue Californian sky. My humiliation on the mat is made bearable only by the surroundings: the class is taking place in a splendid new park on the roof of a recently rebuilt bus terminal in the centre of San Francisco.

As I try to follow the instructions that the teacher is drawling into her microphone, she politely trains her eyes on the sportier enthusiasts rather than my awkwardly contorted body. Like all yoga classes I’ve dared to attend, this one is an utter disaster.

Sales force park