Another option is the biodegradable route, as chosen by so many human civilizations we don't see much evidence of. It was here on HN where I learned about a ci

Another option is the biodegradable route, as chosen by so many human civilizations we don't see much evidence of. It was here on HN where I learned about a city in now-Cambodia (I think) revealed by ground-penetrating radar. I found it fascinating, and I love the idea that awhole city could leave so little evidence.