Nice but no cigar. You start bij looking at structures that lasted thousands of years. So you start with a giant blob of rock (mountain) then carve your cave o

Nice but no cigar. You start bij looking at structures that lasted thousands of years. So you start with a giant blob of rock (mountain) then carve your cave out of it. Have a reliable source of water nearby and carve out a trompe for compressed air. You cant beat a solid state megalithic generator. For heating you carve out a chicken coop with a thin wall bordering the living room. Use finger paint on the walls to explain how everything works and for decoration.