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. Blending reportage, humour and personal encounters, Andrew Martin embarks on a wonderfully engaging social history of London's underground railway system (which despite its name, is in fact fifty five per cent overground). Along the way he attempts to untangle the mess that is the Northern Line, visit every station in a single day - and find out which gaps to be especially mindful of. Underground, Overground is a highly enjoyable, witty and informative history of everything you need to know about the Tube.