Building underground hut with grass roof & fireplace with clay

How long and where did I build?
I been working very hard with my 2 friends about 2months to completely build, This underground hut is in a very small private jungle in California (United State), We did together with three people (2 people is builder and one person is camera man)

How large is it?
Underground Hut Dimension: Depth 3m , width 5.5m, height 3m, I knew the most of viewer they hard to believe but it real 100% by hand made with tools in video ! If you have any ideas, please leave a comment below my video.