Paris is a city of huge positives but also negatives. That's the view of the author of a new book on what he calls an "Impossible City". Simon Kuper, a journalist for The Financial Times, describes in the book how the French capital is not at all simply the picture-postcard city we tend to think of. While 2 million people live in central Paris, another 10 million live in the banlieues, or suburbs. Kuper says he's hopeful that plans to open 68 new metro stations will connect the two parts of the metropolis better. He spoke to us in Perspective.