In Madrid, Spain, a unique, hulking structure is currently being built. An "Air Tree," it's designed to both affect the surrounding environment and act as a social center. It's loaded up with solar panels that create electricity that's sold to the local electric company. It's completely self-sufficient, powering itself and using the money it makes from selling excess energy for upkeep. It also produces oxygen like a tree, hence the name. And as for it being a social center, it's designed to be a public gathering place. It's really pretty cool, a completely unique idea and one that, unlike most out-of-the-box ideas like this, is actually being made a reality.

[Platforma Arquitectura via NotCot.org]