Just a quick one: there’s a great article on io9 about how cities began, and where they’re going. Really interesting stuff.
“Now that the majority of humans live in cities, we’re going to be confronting a new set of problems in urban life. For one thing, natural disasters in cities can cause much greater numbers of fatalities than in sparse, rural communities. So the cities of tomorrow will need to be robust against many kinds of disaster, from earthquakes and floods, to radiation bombardment. It’s possible that many cities will built partly under ground, and partly under water. They might even be built inside a single building surrounded by farms. Not only will such structures allow us to conserve space, but layers of earth and water are excellent protection against radiation.”