And it's been done for at least 2500 years: https://en.wikipedia.org/wiki/Tunnel_of_Eupalinos https://en.wikipedia.org/wiki/Tunnel_of_Eupalinos and more at http

And it's been done for at least 2500 years: https://en.wikipedia.org/wiki/Tunnel_of_Eupalinos https://en.wikipedia.org/wiki/Tunnel_of_Eupalinos and more at https://fermatslibrary.com/s/the-tunnel-of-samos https://fermatslibrary.com/s/the-tunnel-of-samos That tunnel is over a kilometre long, and they met in the middle of a hill!