A "walk through time" has been made possible by a program for the most up-to-date mobile phones that shows users where they are located on ancient maps. The program, developed by a team from Edinburgh College of Art and the University of Edinburgh, uses global positioning technology to allow users to explore the city via maps that are hundreds of years old. Chris Speed, one of the developers, said: "The great fun is giving it to someone and then taking them to where a street doesn't exist and saying 'walk', when there's a new building in the way. They begin to realise that the world has changed." The project was funded by the Joint Information Systems Committee.