Rio Tinto Group is an Anglo-Australian multinational company that is the world's second-largest metals and mining corporation (behind BHP). The company was founded in 1873 when of a group of investors purchased a mine complex on the Rio Tinto, in Huelva, Spain, from the Spanish government. It has grown through a long series of mergers and acquisitions. Although primarily focused on extraction of minerals, Rio Tinto also has significant operations in refining, particularly the refining of bauxite and iron ore. Rio Tinto has joint head offices in London (global and "plc") and Melbourne ("Limited" – Australia).