Show Hide image 20 November 2012 Chart of the day: silicon valleys and roundabouts A report from Telefonica digital and Startup Genome examines the startup ecosystems in 20 cities worldwide, including London. Byt what are the simliarities and differences between Silicon Roundabout - the Old Street area in London - and Silicon Valley? By Alex Hern Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.