Driving 60km east of Rancágua will take you to the land of underground mines. El Teniente or 'the lieutenant' has 1500km of tunnels and the largest number of underground mines in the world. Owned and managed by Codelco, the mine is open to public tours but requires prior permission. Organized tours include bi-lingual guides and transport. A 5-hour tour includes a visit to the abandoned company town of Sewell and travelling down the shafts to the underground tunnels. For adventure enthusiasts there is a ski resort nearby owned by Codelco and offering 7 sq km of ski slopes, chairlifts, draglifts and even homes for rent.