Corta Atalaya is the largest open-pit mine in Europe and was at one time the largest in the world. It is located within the city limits of Minas de Riotinto in the province of Huelva, autonomous community of Andalusia, Spain. It is roughly elliptical in shape, 1,200 metres (3,900 ft) long, 900 metres (3,000 ft) wide, and 350 metres (1,150 ft) deep. It was one of the most ambitious projects of the Rio Tinto Group. At its peak it employed 2,000 workers mining copper; it was actively mined until 1992. Since at least 1994 it has been flooded up to the 16th ring.

This open-pit mine in the western part of the Masa San Dionisio was begun in 1907 after major subsidence in some of the higher-altitude parts of the area two years earlier, caused by the combustion of pyrites in the earlier subterranean mines. The mines were nationalized in 1954 but later sold back to a private company. As of October 2009, the current owner, EMED Tartessus, says they will have the mine operating again before the end of 2013.