Triumph of the City on Hobo's recommendation. It talks about human history and makes some predictions about the future based on understanding what exactly cities do for humans from a wide variety of perspectives. The main thing cities accomplish is to promote innovation though ease of contact with other people. Although smart people can do a lot of things their accomplishments are always orders of magnitude greater when they have access to other smart people to help nurture their ideas and push them in unusual directions. Many a time in the recent past people have talked about how telecommuting and other improved communication tools will allow workers to get back to the country while still being very productive but we have not seen that occur; the face to face contact that living in a city facilitates is just too powerful.
Cities are particularly interesting to me because of the way in which they are portrayed in environmentalist texts and thought. Often the incredible amount of waste cities produce is vilified and cities are regularly seen as the symbol of excessive human consumption and overpopulation. While humans do consume too much and are too populous cities aren't the source of that but rather they are part of the cure. Spreading everyone in the world out into the country would increase our resource consumption and environmental impact drastically because those who do live in the country use far more power / water / oil / etc. and have a massively higher carbon footprint. If we want to make the world a cleaner and more sustainable place a great way to start would be to cram everyone into gigantic shining towers in huge metropolises, not to encourage us to all get back to nature.
The author, Edward Glaeser, has some views on taxation, unions, and law enforcement that I don't agree with. He swings too far to the right politically for my taste, which isn't to say he is a tea partier or anything but it isn't as if I can give everything in the book a resounding thumbs up. That said I do very much like his ideas on promoting education and creativity rather than infrastructure and stagnation. He thinks that people define cities, not buildings, and that cities are best seen as a group of individuals rather than a place. Looking at them this way gives us lots of insight into how to make cities better places to be for everyone. He wants cities to be places where the incredible numbers of connections between people lead to amazing and wonderful innovations. I can't argue with that.