Rammed Earth Building (like the Great Wall)

Rammed Earth or Stabilized Earth building technique is basically building solid earth walls by compressing/compacting a mixture of earth, sand and may be some cement in place, using "forming" devices like a wooden shell. Once the earth is dry, the forming device is removed, and the next section of the wall is rammed in.

Benefits:

Thermal Flywheel Effect - the earth stores heat during the day and releases it at night
Indoor air quality
Longevity, durability, low-maintenance
Fire and Insect resistance
Environmentally Friendly
Intangibles - great feeling, quietness of solid earth walls...

Recently, MIT researchers experimented with a building technique used more than 2000 years ago in the Great Wall of China. They used local Boston blue clay, mixed it with two parts sand and gravel, packed the mixture by hand and a pneumatic compactor into a wooden shell that was removed once each section was complete and dry. The wall which was started in September 2005 is apparently doing just fine 2 months later.

This technique will not be suitable for applications where strength is important. However, a neat application, for example, would be for building the acoustic proofing walls by the side of highways. Apart from looking more aesthetic, thanks to the wall essentially being made of the same material as the surrounding land, it'd be environmentally friendly too, as much of the material used uses little processing.