Oficina salitrera Pedro de Valdivia, Saltpeter works in Atacama Desert, Chile

The Oficina salitrera Pedro de Valdivia is an abandoned nitrate works in the Atacama Desert, 99 km southeast of Tocopilla. Its long, low buildings of pale sandy walls have wooden doors and dark shutters, and the roofs are now bare grids of wooden beams open to the sky. The camp was laid out along avenues named Diego de Almagro and Bernardo O'Higgins, with solid passages such as Ossa and Puelma for single workers.

Construction of Pedro de Valdivia began on 5 January 1930, and the first saltpeter was processed on 6 June 1931, the date still celebrated as its day. Built to apply the Guggenheim system, it was the last saltpeter office raised in Chile. The company passed to Soquimich in 1965; the site was abandoned in 1996 and declared a National Monument in 1999.

The town's 27 streets and avenues were named after national figures, but the names also recalled other saltpeter offices of the same company. Each 6 June, the date of the first nitrate output in 1931, is celebrated as Pedro de Valdivia Day on the nearest Sunday. Former residents return for a small celebration in the first week of June.

Access is via the CH-25 highway from Tocopilla, about an hour's drive, and the final stretch requires a four-wheel-drive vehicle. Bring plenty of drinking water and sunscreen. The site lies in the El Toco canton, roughly 100 km from the port of Tocopilla and 160 km from Antofagasta.

The complex operated its own monetary system where workers received payment tokens usable only in company stores. This arrangement kept workers economically tied to the facility.