Sewell is an uninhabited Chilean mining town located in the commune of Machalí in Cachapoal Province, Libertador General Bernardo O'Higgins Region, on the slopes of the Andes, at an altitude between 2,000 and 2,250 metres. The town was founded in 1904 by the Braden Copper Co. to extract the copper in the El Teniente mine, and, in 1915, it was named after the company's first president, Mr. Barton Sewell. In 1918, it already housed 14,000 people.
Following many years of active life and achieving the construction and exploitation of the largest underground mine in the World, in 1977 the company started moving families to the valley and soon after the camp was being dismantled. The Chilean Government declared Sewell a National Monument in 1998, while the UNESCO designated it a World Heritage Site in 2006. Sewell is known as the city of stairs as there were no roads, only a train that brought workers and their families to the camp. Visiting the site is only allowed to tour operators, it's not possible to access the area with private vehicles. Tour operators are available in Santiago and Rancagua.