underground housing

I am northwestern native american. my ancestors have built pit housing for time imimorial . i now have built 3 before and helped build another that the individual started but did not know how to finish. 2 were built tradtional. the third was built contemperary. basically 3 stories under ground with not only cement and rock walls but with a fireplace, root cellar and hard wood flooring as well with  7 windows  ranging from 2'x2' to 7'x2'. i used cedar as well as fur for my suports and roofing. once i buried the house i built a house on stilts above ground on top of the one enterance of the pit house.

the building due to how it is constructed does not need nails, yet the adding of the windows and doors i did use nails and screws.

my idea now is to expand such a idea all across the country as well as around the world if or when i find the founding to make another such dwelling again. 

I feel this kind of housing , especially in the area's where tornato's are rather frequent i believe this kind of housing would be more suitable then above ground dwellings. The benifits of underground housing is not only climate and energy efficiantcy but as well remote areas where forest fires could be a problem, mother earth only burns 2 to 3 inches and the rest of her remains untouched.

I have many plans and designs not only on paper but in my head. i am not only looking for founding but partnership to the right enthusicastic individuals that see a project like this expanding

The pic i set forth is a picture of what my pit house i lived in for about 3 yrs. It shows the begining of what eventually turned out to be a split level 3 story pit house .I started to build a house on top of the pit house as well built on twelve beams that i was carving into totom polls. Added also was a 350 sq foot root cellar

once i figure out how to put a picture up i will show some of the pithouses i built to date.