Skyscrapers towering over major cities or spectacularly-designed bridges often come to mind when we think of great feats in architecture and engineering. However, some of the most amazing, creative, and innovative structures on earth are not man-made or urban at all, but residences built by animals in the natural world. Termites across Africa's plains build ten-foot-high mounds, temperature-controlled high-rises maintained by solar power and complete with flood contingency plans. Leaf and grass cutter ants move 40 tons of earth to create subterranean cities with highways, homes, farms, trash pits, and nurseries for 12 million residents. Army ants create living houses made entirely of their own bodies. Cave swiflets mold crystal nests from their gluey saliva. New Guinea's male Vogelkop bowerbirds, meticulous interior decorators, use their artistic visions to woo. Beavers build enormous dams, changing the landscape to create a safe environment for their lodges. And hummingbirds delicately weave tiny camouflaged cradles out of cobwebs, grass, twigs, and leaves. Guided by instinct, animal architects build an remarkable variety of elaborate dwellings with their simple supplies. Every house suits the needs of its owner, to shelter and protect. NATURE investigates what goes into making a home when you're wild and cost is not a factor. They may be single-use, multi-generational, or multi-purpose; they may be anything from a small depression in the sand to a many-chambered tunnel, a nest, a burrow, or a mound, but for animals big and small, these dwellings are always impressive home sweet homes.