Loved it. What about... tunnels ? I wish he mentioned it. My uneducated guess is that probably, again, technology was a limiting factor and it would not have be

Loved it. What about... tunnels ? I wish he mentioned it. My uneducated guess is that probably, again, technology was a limiting factor and it would not have been worth while to dig out tunnels because either too slow, not deep enough or too much rock.