efe-epaBy Alberto Peña Machali, Chile

Chile's El Teniente copper mine, the world's largest underground mine, has gone from using donkeys during its early days in 1905 to using remote-controlled dump trucks today, reflecting a commitment to keeping this huge facility viable for another half century in the interior of the Andes.

More than a century has passed since miners using picks and shovels began digging the first tunnels in the mountain, located about 85 kilometers (some 53 miles) south of Santiago.