In Madrid, the capital of Spain, a huge structure called the "Air Tree" is currently under construction. It is designed to both affect the surrounding environment and act as a social gathering point for people.
The "Air Tree" will generate its own electricity using solar photo voltaic cells placed on top of it. The solar panels will generate enough electricity to be able to sell the energy to local energy companies.
Inside the structure trees will be planted to produce oxygen, just like an ordinary tree. Due to this the surrounded areas will get a cooler temperature. It is expected that during summers it will be 8-10 Â°C cooler inside and nearby the "Air Tree". More trees will be planted around the structure to enhance the cooling effect.
The "Air Tree" will be built with recycled materials and has been co-financed by the Housing and Land of the City Council of Madrid and by the European Union under the LIFE programme-2002 (ENV/E/000198).
You can find more information, in Spanish, and pictures of the "Air Tree" over at Plataforma Arquitectura.