Manhattan may be one of the world's liveliest and richest places, but it is a slender island just 21 kilometers long and very crowded. Its buildings have been getting taller and taller. Many buildings from previous centuries need to be upgraded or replaced. The infrastructure is also severely strained. So large-scale eco-friendly redevelopment is on the cards, and the creation of neighborhoods that are pleasant places to live and work. Another urgent issue is flood prevention as sea levels rise. New York will need to stand its ground as cities compete for the best and the brightest.