We explore how individual animals, sometimes working together, shape their world in designing and constructing their homes and shelters. In South-East Asia the orangutan has mastered structural design to build their secure sleeping platform every night high in the trees. In southern Africa some weaver birds build the great communal nests that can last for a hundred years. But the master builder of all is the beaver, an aquatic rodent that alters the flow of rivers to shape the world around them.