Okay, not quite into the wooly mammoth era but try hopping in your way-back machine to about 1400 BC and watching the Hittites breaking ground on a 20-story deep underground city with a tunnel leading to another underground city EIGHT MILES AWAY!
They did this nearly three and a half thousand years ago! Shovels and pick-axes were like i-phones to these people and they out-tunneled the Viet Cong, the Mexican Mafia and Ocean’s 14 all put together!
Just wanted to give credit where credit is due, however belatedly.
