La Oroya is a city on the River Mantaro and capital of the Yauli Province, located in the Department of Junin in central Peru. It is situated on the eastern watershed of the Andes at an altitude of 3,745 m, some 176 km east-north-east of the national capital, Lima. La Oroya is the location of a smelting operation that earned the town a place on the Blacksmith Institute's 2007 report on "The World's Worst Polluted Places". It is also the eastern endpoint of the Central Highway of Peru (Carretera Central). History In 1533, the Spanish established a small settlement and started small-scale mining for precious metals in the area, but isolation and transport difficulties hindered extraction. At the time of the War of Independence, the area's strategic position made it a center of guerrilla activity; one of the decisive battles of the war, Chacamarca (Junin), took place nearby, and Simón Bolívar passed through the town after the battle. In 1861, the settlement was named San Jeronímo de Callapampa and in 1893 it became La Oroya. In 1925, La Oroya was designated the capital of the Yauli province and finally, in 1942, it was elevated to city status. Mining in the area developed gradually and did not greatly expand until the Ferrocarril Central Andino railway from Lima was completed in 1893. The railway, an extraordinary feat of engineering, was planned by the Polish railway builder Ernest Malinowski and crosses the Ticlio Pass, where it reaches an altitude of 4781 meters. Until the recent completion of the Qinghai-Tibet Railway it was the highest standard gauge railway in the world. The smelter, now the city's main employer, was established in 1922 by the American Cerro de Pasco Corporation, who ran it until 1974 when Cerro was nationalized and became part of the state-owned Empresa Minera del Centro del Peru S A, otherwise known as Centromin. In 1993, the Peruvian government decided to privatize Centromin. In 1997, 99.97% of the La Oroya smelter was acquired by Doe Run Peru, a subsidiary (now an affiliate) of the Renco Group, for approximately US$247 million. The acquisition consisted of a capital contribution to Centromin's Metaloroya of US$126.5 million and a purchase price payment of US$120.5 million. Doe Run Peru also bought the Cobriza copper mine for US$7.5 million to maintain concentrate supplies to the copper smelter. Economy Mining and Metallurgy First, to be built was the copper