Pedra Salgadas, Portugal
The Tree Snake Houses got their name from their long ramps, not because they're poised to reach out and bite you. In fact, just the opposite: The prefab structures, assembled offsite with local, natural materials, are decidedly low on environmental impact. The structures' creators, Luis and Tiago Rebelo de Andrade
, are working on adapting their design to other environments, such as river banks, mountains, and urban centers.