Web developer Chris Gray came up with his idea for a global Underground map (pictured) when he was visiting Australia and suddenly wanted to 'nip home'. He picked the stops by  picking 'nodes' at densely populated cities and worked out the connections from thereSome train journeys feel like they take forever – especially when there are numerous transfers and waits in between flights and trains. But what if you could board a train in Madras, India and travel to Boston with no changes? One man has imagined the world as a giant London Underground map where people can travel freely between countries and traverse vast bodies of water from the comfort of their seat while vehicles speed through vast tunnels. While his dream is currently ‘impossible’, engineers are constantly trying to develop new ways to connect countries. More