Declared Bien de Interés Cultural in 2013, the Pozu San Luis in the Valle de Samuño now forms the centrepiece of the Ecomuseo Minero Valle de Samuño, with its intact modernist engine house and robloned steel headframe fully open to visitors.
Pozu San Luis is a closed bituminous coal shaft situated in the valley of the river Samuño in the concejo of Langreo, Asturias. The area had been worked by mountain mining since the nineteenth century, with the Socavón Isabel and the Socavón Emilia dating from 1896 and 1904 respectively. In 1925 the company Carbones de La Nueva was acquired by the Real Compañía Asturiana de Minas (RCAM), which required a coal supply following the closure of its Arnao mine in 1915.
Between 1928 and 1930 RCAM profundised the vertical shaft. The shaft reached 420 metres across six working levels, though the sixth was never worked due to permanent flooding. The riveted-steel headframe and the large modernist engine house, with its distinctive stepped pediments and zinc pinnacles, both date from 1928 to 1930.
The engine house was extended in 1945 while preserving its original appearance. Hunosa integrated the shaft in 1968 and used it as an auxiliary of the neighbouring Pozo Samuño until extraction ceased in 1969. The shaft served maintenance functions until definitive closure in 2002.
In 2008 the Ayuntamiento de Langreo received the property from Hunosa. The shaft was declared a Bien de Interés Cultural as a Conjunto Histórico by Decreto 14/2013. The Ecomuseo Minero Valle de Samuño, which uses the shaft as its centrepiece, opened in June 2013.
The valley of the river Samuño, a tributary of the Nalón, has been a site of coal extraction since at least the mid-nineteenth century. Mountain mining — the exploitation of seams above valley level through horizontal galleries driven into the hillsides — characterised the first period of activity. The Socavón Isabel dates from 1896, and the Socavón Emilia from 1904; the latter, part of the Carbones de La Nueva operation, forms part of the present ecomuseum visit as its underground entry point.
From the early twentieth century, Carbones de La Nueva was the principal operator in the valley, alongside the neighbouring Carbones Asturianos, which worked the Pozo Samuño on the same valley floor. In 1925 Carbones de La Nueva was acquired by the Real Compañía Asturiana de Minas (RCAM), a company whose zinc-smelting operations had depended on coal from its own Arnao mine until that colliery was closed in 1915. The acquisition of Carbones de La Nueva gave RCAM access to the Samuño valley reserves, and the company thereupon undertook the transition from mountain mining to vertical shaft extraction.
Between 1928 and 1930 the vertical shaft was sunk and the main surface infrastructure was constructed: the riveted-steel headframe, standing approximately 25 to 28 metres in height, and the engine house, which accommodates the extraction machine of 1929, the compressors, and the winding apparatus. The engine house is architecturally distinguished, with a principal façade of three bays articulated by pilasters and crowned by stepped pediments with zinc pinnacles of baroque inspiration, together with three decorative ceramic plaques. The building was extended in 1945 without substantially altering its appearance; the left wing dates from this later phase.
Coal extracted at the shaft was transported by railway down the Samuño valley to the Nalón and onward to the RCAM's coastal zinc-smelting facilities. The shaft reached a total depth of 420 metres across six working levels. The sixth level was never exploited in practice as it remained permanently flooded.
In 1968 the shaft was integrated into Hunosa along with the Carbones Asturianos operations in the same valley. Hunosa thereafter used the Pozo San Luis as an auxiliary for the neighbouring Pozo Samuño. Active extraction at San Luis ceased in 1969.
In its final years, the 1929 extraction machine continued to perform maintenance functions for the Pozo Samuño until that shaft also closed in 2002, at which point the Pozu San Luis was definitively closed as well. On 31 October 2008 the installations passed to the ownership of the Ayuntamiento de Langreo by agreement between Hunosa and the municipality, in preparation for the ecomuseum project. By Decreto 14/2013 of the Principado de Asturias, signed on 6 March 2013, the Pozu San Luis was declared a Bien de Interés Cultural with the category of Conjunto Histórico.
The declaration noted that the shaft and its associated buildings, including the engine house, the headframe, the lamproom, the washhouse, the offices, the workshop, the medical room, the forge, and the carpenter's shop, constituted one of the most outstanding examples of the industrialisation of the central mining valleys of Asturias. The BIC declaration had been initiated by resolution of the Consejería de Cultura y Turismo on 9 November 2009, and received favourable reports from the Comisión de Urbanismo y Ordenación del Territorio de Asturias, the Real Academia de la Historia, and the Real Academia de Bellas Artes de San Fernando. The Ecomuseo Minero Valle de Samuño was inaugurated in June 2013, financed with Fondos Mineros from the 1998–2005 restructuring plan.
Visitors arrive at the Estación de El Cadavíu, where they board a narrow-gauge mining train that travels approximately two kilometres along the former coal railway of Carbones de La Nueva, passing through the Socavón Emilia gallery, the longest underground railway traverse in a working mine gallery in Spain, before arriving at the Pozu San Luis at a depth of 32 metres on the first level. The surface pithead buildings serve as exhibition spaces covering the history of mining, mining techniques, social organisation, safety, and the valley landscape. The ecomuseum recorded more than 13,000 visitors in its first summer season and reached a visitor record in 2024.