We dug out our basement and finished it to add a gym, home theater, and golf simulator. 80,000+ pounds of dirt and concrete out, 30,000+ pounds of concrete back in. Glad I did it - won't do it again. Oh, the gravel and plastic are for radon, not carbon monoxide - and it worked!
If you liked this project, subscribe and check out our remodel and kitchen addition on an 1880 house: https://youtu.be/D9lDYcZQMAA