Underground, overground

Why is the Victoria Line so hot? What is an Electrical Multiple Unit? Is it really possible to ride from Kings Cross to Kings Cross on the Circle line?The London Underground is the oldest, most sprawling and illogical metropolitan transport system in the world, the result of a series of botch-jobs and improvisations. Yet it transports over one billion passengers every year - and this figure is rising. It is iconic, recognised the world over, and loved and despised by Londoners in equal measure.