About 90 percent of the world’s largest cities are located along waterfronts. Koen Olthuis of Dutch architectural firm Waterstudio.NL believes that with climate change leading to drastic rises in sea levels, we'll need to rethink how we live with water in the built environment. His team has designed sophisticated floating homes like Watervilla De Hoef and Watervilla IJburg in the Netherlands, and is working on masterplans for floating apartments, social housing developments, and even cities.