This Iron Age (roughly 1200 to 500 B.C.) structure was likely built with little regard for green building -- at least in the modern sense. The Earth House, located near the city of Dundee, was discovered in early 1949. Over the following year, archaeologists excavated the site, which consists of a series of interlinked huts and underground cellars.
This in and of itself isn't particularly remarkable; archaeologists suggest that this type of construction was common in this location and era [source: Royal Commission on the Ancient and Historical Monuments of Scotland]. From a green building perspective, however, the Ardestie Earth House site offers evidence that our ancestors knew a thing or two about green building even though it would be centuries before the term came into use.
The earth is a very good insulator and building material. Many of the historic green homes on this list make use of earthen walls, or they simply build into the earth rather than on top of it. Not only does this save significant amounts of energy, but it also reduces the amount of material needed to construct standing-room-height interiors. The people who constructed Ardestie Earth House and similar structures in Scotland were likely focused on making the most of the building materials they had and on finding a way to stay as warm as possible during the cold winters. Little did they know that their home incorporated green design features that would be touted by builders centuries later [source: Freed].