damp sub-soil are placed inside the forms and pounded to total compaction and the process is repeated until the desired height is achieved. What is left after the forms are removed is a wall that is structural and can last over 1000 years. Stone Stone has been used as a building material for thousands of years. It has long been recognized as a material of great durability. The pyramids in Giza, burial chambers in the UK and temples in Malta were all built from stone over 4000 years ago and are still standing. The earliest form of stone construction is known as dry stone, or dry stacking. These are freestanding structures such as field walls, bridges and buildings that use irregularly shaped stones carefully selected and placed so that they fit closely together without slipping. Structures are typically wider at the base and taper in as height increases. They do not require any special tools, only the skill of the craftsman in choosing and placing the stones. Traditional stone masonry evolved from dry stone stacking. Stone blocks are laid in rows of even (courses) or uneven (un-coursed) height, and fixed in place with lime mortar pasted between the stones. Traditional stone masonry is rarely used today because stone is expensive to quarry, cut and transport, and the building process is labor and skill-intensive. Stone is a highly durable, low maintenance building material with high thermal mass. It is versatile, available in many shapes, sizes, colors and textures, and can be used for floors, walls, arches and roofs. Stone blends well with the natural landscape, and can easily be recycled for other building purposes. Straw bale Although grasses and straw have been in use in a range of ways in building since pre-history around the world, their incorporation in machine-manufactured modular bales seems to date back to the early 20th century in the midwestern United States, particularly the sand-hills of Nebraska, where grass was plentiful and other building materials (even quality sods) were not. Straw bale building typically consists of stacking a series of rows of bales (often in running-bond) on a raised footing or foundation, with a moisture barrier between. Bale walls are often tied together with pins of bamboo or wood (internal to the bales or on their faces), or with surface wire meshes, and then stuccoed or plastered using either lime-based formulations or earth/clay renders. Bale buildings can