Humberstone And Santa Laura Saltpeter Works, Atacama Desert, Tarapacá, Chile

However the economic model collapsed during the Great Depression of 1929 because of the development of the synthesis of ammonia by the Germans Fritz Haber and Carl Bosch, which led to the industrial production of fertilizers. Practically bankrupt, both works were acquired by COSATAN (Compañía Salitrera de Tarapacá y Antofagasta) in 1934. COSATAN renamed La Palma into "Oficina Santiago Humberstone" in honor of its founder. The company tried to produce a competitive natural saltpeter by modernizing Humberstone, which led to its becoming the most successful saltpeter works in 1940.
Both works were abandoned in 1960 after the rapid decline that caused COSATAN to disappear in 1958. In 1970, after becoming ghost towns, they were declared national monuments and opened to tourism. In 2005 they were declared a World Heritage Site by UNESCO.
Description from UNESCO World Heritage Site web site