Sewell is a populated Chilean mining town located on the slopes of the Andes in the commune of Machalí in Cachapoal Province, Libertador General Bernardo O'Higgins Region, at an altitude of between 2,000 and 2,250 metres.

While some buildings were demolished in the 1980s, others have now been renovated for contract workers, and restored as part of preservation of this historic site.

The narrow gauge railway that connected Sewell to the nearby town of Rancagua, 32 kilometres (20 mi) away, was under construction in 1906 and was completed in 1911.

[2]: 126  The buildings and homes were made out of timber, and painted bright colors such as yellow, red and blue.

[2]: 128  Additional, ever-present threats to the city included earthquakes, avalanches and explosions from mine operations.

[1][2]: 128 In 1967 the Kennecott Copper Corporation relinquished its sole ownership of the site when the Chilean government bought a 51% stake in the company.

In 1977, the state-owned CODELCO (Corporación Nacional del Cobre de Chile) started moving more families out of Sewell into the valley.

The company town had been active for more than seven decades, and supported the construction and exploitation of the largest underground mine in the world.

Numerous supporters argued to have the town preserved because of its significance to Chilean history and its unusual site in the Andes.

In 1999 Chile's College of Architects declared Sewell to be one of the country's 10 most important urban works.

[6] In 2006 UNESCO designated it as a World Heritage Site, based on Chile's nomination and assessment of its significance.