About 40 miles east of the provincial city of Rancagua up in the Andes is El Teniente, the largest underground copper mine in the world. The now abandoned mining town of Sewell, located high in the mountains, was built in the early 20th century for families of the miners.
First called "El Establecimiento" in 1904, it later became known as "Sewell" under the then Braden Copper Company. In 1967, the Chilean government bought the majority of shares, nationalizing the mine, and today it belongs to CODELCO (the state-owned copper company). Sewell has long been abandoned by the families and miners but is now considered national heritage for its unique location and architecture.
You can take scheduled visits both of El Teniente (not for those with claustrophobia) and Sewell.