Imagine what life would be like floating around the world on a giant island capable of holding 50,000 people and completely sustaining itself. Well, welcome to "Lilypad City." Designed like a lily pad, the innovation by award-winning Belgian architect Vincent Callebaut could be used as a permanent refuge for those whose homes have been covered by water in the future. "I think trying to accommodate the millions of people left homeless by environmental changes will prove to be one of the great challenges of the 21st century," he told the Daily Mail. "Some countries spend billions of pounds working on...