The Río Tinto mining railway is among the most iconic in Spain. Although its main purpose was to transport pyrites and copper from these mines – massively exploited thanks to British investment – it also carried passengers and all manner of goods. In 1873, The Rio Tinto Co. Ltd. purchased the historic Río Tinto mines from the Spanish state. Moving ore to the coast for export was an urgent necessity, and the railway was clearly the most effective solution. After a turbulent concession process, construction began that same year on an 84-km line built to the unusual British gauge of 1,067 mm. To this were added no fewer than 264 km of additional sidings, spurs, branch lines, and access tracks to mines and loading bays.

The line was inaugurated in 1875, running alongside the Río Tinto for its entire length to Huelva, where the company built its spectacular loading pier on the Odiel estuary – a remarkable structure still standing today as an industrial heritage landmark. From Niebla to Huelva the railway ran parallel to the Seville–Huelva line, crossing at San Juan del Puerto with another mining railway, the line up to the Buitrón mines.  At its eastern end, the Río Tinto railway had branches to Zalamea (where it connected with the Buitrón line) and to Nerva, which linked with other mining lines extending as far as Seville, forming part of a complex network of narrow-gauge mineral railways. 

The British phase of mining and rail ended in 1954, when it was acquired by the Compañía Española de Minas de Río Tinto, S.A. Interestingly, the British company continued operating elsewhere in the world under its Spanish name until 1978. The scale of its rolling stock was extraordinary: 143 steam, 10 diesel, and 7 electric locomotives, 1,200 wagons, and around 2,000 mining trolleys, plus auxiliary stock.  Traffic on the line was immense, but the decline of mining led inevitably to its closure: passenger services ceased in 1968, and the line closed completely in 1984. From that former glory, one stretch has survived: an 11-km section that, since 1994, has been operated as a Tourist Railway through the mining zone, running from Río Tinto to Los Frailes.