The oldest continually operating mine in Europe and the world's first uranium mine, still active at Jáchymov supplying radon water to the town's therapeutic spas, with a replacement headframe of 1992–1996.
Důl Svornost at Jáchymov is the oldest continually working mine in Europe and the first mine in the world where uranium was systematically extracted. Founded in 1518 under the name Kliment on the intersection of two silver veins, it was renamed Svornost (Einigkeit, meaning Concord) in 1530 following the settlement of a dispute between two competing mining companies. Silver and later cobalt and arsenic ores were extracted across several centuries.
Systematic uranium extraction began in 1853 for the production of uranium dyes, and in 1864 a powerful underground spring struck at the 12th level produced the radon-rich water that gave rise to the world's first radon spa in 1906. State ownership was established in 1850. The mine buildings were entirely rebuilt in 1922–1924 to designs by architect Milan Babuška.
During the post-war communist period uranium mining was intensified using forced labour including political prisoners; a labour camp operated adjacent to the mine from 1949. Uranium extraction ended in 1964 and the mine was transferred to Léčebné lázně Jáchymov, which has operated it since as the sole source of radon water for the Jáchymov spas. A general reconstruction was carried out between 1992 and 1996, replacing the headframe and installing a new electric winding engine.
The Jáchymov Mining Landscape, including Důl Svornost, was inscribed as a UNESCO World Heritage Site in 2019 as part of the Erzgebirge/Krušnohoří Mining Region.
Důl Svornost was founded in 1518 on the intersection of two rich silver veins, the Stella (also called Geschieber) and the Svatý Ondřej (Saint Andrew), by a Rhenish miner named Georg Schweitzer, who named it Kliment. In the first year of production the mine yielded a net profit of 40,000 gold coins. The richness of the deposit immediately generated a dispute over mining rights between two consortia — Pokolení sv. Anny and Sv. Anny Bohatý valoun — which was resolved by their merger in 1525. The name Svornost (in German Einigkeit, meaning Unity or Concord) was adopted in 1530 to commemorate this settlement.
Throughout the sixteenth century Důl Svornost was among the most productive mines of the Jáchymov district, which at its peak made Jáchymov the second most populous town in the Kingdom of Bohemia. Silver, cobalt, arsenic, nickel, and bismuth were all extracted at various periods. In the seventeenth and eighteenth centuries cobalt ores became the principal product, supplying the production of blue cobalt pigment, much of which was exported to Saxony. In 1764 the mine passed from private to municipal ownership, the town having also acquired jáma Josef. In 1801 the town sold the mine back to face growing costs from groundwater problems; financial pressures led the state to take it over in 1850.
By the early nineteenth century the mine had reached a depth of 292 metres. By 1848 it had been deepened to 419 metres and equipped with two water-column machines for hoisting and pumping. In 1850, as the state assumed control, the mine's character began to change. Uranium ore (pitchblende, smolinec) had been a by-product of silver extraction for decades, but from 1853 systematic extraction of pitchblende for the manufacture of uranium dyes in the state factory at Jáchymov made Důl Svornost the world's first dedicated uranium mine. In 1864, at the 12th level at a depth of approximately 532 metres, miners struck a powerful underground spring. Locals noted unusual properties in the water and termed it the Zázračný pramen (Miraculous Spring). In 1905 the mining company had the water analysed by Viennese physicists Stefan Meyer and Heinrich Mache, who established its high radon content. The world's first radon spa was opened in Jáchymov in 1906, initially in a private house. The spring discovered in 1864 was later named after Marie Curie-Skłodowska, whose isolation of radium from Jáchymov pitchblende waste in 1898 had established the scientific basis for radon therapy. A further radon spring tapped in 1924 is known as Pramen Curie.
The shaft buildings were comprehensively rebuilt in 1922–1924 to designs by the prominent Czech architect Milan Babuška, and parts of these buildings survive within the current shaft complex. In 1946 the mine was incorporated into the newly formed national enterprise Jáchymovské doly. The shaft building was raised in height, a more substantial headframe was constructed, and a single-storey office wing supported by a massive wall was added.
The post-war period brought the darkest chapter in the mine's history. Uranium assumed strategic importance for the Soviet nuclear weapons programme, and a Czech-Soviet agreement on uranium exports was signed in 1945. Production was rapidly scaled up under Soviet direction: the 300 workers employed in 1945 grew to over 40,000 across the Jáchymov district by the 1950s. A forced labour camp was established adjacent to the Svornost mine in 1949, one of twelve such camps around Jáchymov collectively known as Jáchymovské peklo (Jáchymov Hell). Approximately 700 mostly political prisoners were detained in the Svornost camp and forced to work in the uranium mine. Uranium mining at Důl Svornost ended in 1952 according to some sources, and across the district in 1964. On 1 April 1964 the mine and its staff were transferred to Léčebné lázně Jáchymov, which has operated it since exclusively for the extraction of radon water.
A general reconstruction of the mine was carried out by Léčebné lázně Jáchymov between 1992 and 1996. The shaft was lined with concrete to the 12th level (500 metres underground) and fitted with new support structures, the corroded headframe was replaced with a new one, and the engine room was equipped with a new electric drum hoisting machine. In 2002 drilling at depth reached 600 metres and discovered additional radon springs including Pramen Agricola. Four springs are currently extracted: Curie (1924), C1 (1960), Běhounek (1962, the most productive at 280 litres per minute), and Agricola (2000). The underground system of Důl Svornost is connected to jáma Josef, which serves as the intake ventilation shaft, while Svornost and the Rovnost shaft form the exhaust. The total length of underground workings exceeds 160 kilometres.
In 2015 the 232 stairs and the fenced corridor connecting the mine with the site of the former forced labour camp were restored, and replicas of the original watchtowers were constructed to commemorate the prisoners' fate. The Jáchymov Mining Landscape, comprising the Svornost mine and the Věž Smrti uranium processing site among other elements, was inscribed as a UNESCO World Heritage Site on 6 July 2019 as part of the Czech-German Erzgebirge/Krušnohoří Mining Region nomination.