Rammed earth homes are like building sand castles without that tricky step of flipping the bucket. Instead, the form of the home, which is usually a plywood structure that provides the outline of a wall, is already in place. A cross-grade, or mix, of soils is rammed into the walls, either by hand or machine. When everything is packed tightly, the forms are removed, and what's left is a solid, stable wall. Builders ram and repeat until the entire house is built.
So how long do these structures last? Apparently over 2,000 years as parts of the great wall of China were built using this method. Rammed earth homes have a lot of other benefits as well including being fireproof! Additionally, rammed earth walls contain excellent thermal mass. If you're visiting a rammed earth home in summer, you'll find the home to be nice and cool during the daytime, without the aid of an air conditioner or fan. If you're staying overnight, the home will begin to warm up as it cools down outside. This is due to the thermal flywheel effect. The walls hold in warmth and exude it about 12 hours later.
Click the link to see some awesome pics and read more about rammed earth construction.