earthhouse

An underground chamber or habitation; a souterrain.

There were many other heirlooms heaped inside the earth-house, because long ago, with deliberate care, some forgotten person had deposited the whole rich inheritance of a high-born race in this ancient cache.

A dwelling that has been built to blend in with the surrounding landscape, being mostly underground with a grassy contoured roof; it may also be completely underground, or have a topping of intensive growth.