today it serves as a training facility for the montana tech school of mines & engineering. - there's five generations of mining here. in order to survive and provide the resources for america, these people were super skillful. bourdain: jim keane is a state senator and labor advocate who grew up working the mines of butte. how many miles of tunnel under butte, total? - 10,000 miles of tunnels. - 10,000 miles. - and i figure-- - like this? - like this. only smaller, usually. bourdain: larry hoffman is a longtime mining engineer and instructor. matt krattinger is the new guy. a hard-rock miner by day, he likes to relax by spending his free time down here, playing. - i come mining for fun on my days off. - okay. - it's one of those things that just gets in your blood. you got a lot of pride in it. bourdain: these guys like it underground. and even more, they seem to like drilling holes deep into the rock face. [percussive music] [drill squeals and whirs]