The iron ore mine in the village of Kleinerbremen near Porta Westfalica was established by Johann Dinnendahl in 1835, and the nearby Eisenerz Pit was opened in 1883. The workings closed during the 1920s but were resumed, with some open cast pits as well as deep mines, in 1935. The Klenenbremen mine ceased working in 1957 but mining elsewhere in the area continued into the 1960s. A show mine opened in 1988, enabling visitors to see a blue lagoon underground which is attractive to divers, but a new museum opened in 2014. It shows the impact of mining on the landscape, particularly the various means of transporting iron ore, and the effects of mining on biodiversity. There is an imaginative reconstruction of a journey through the history of the earth from carboniferous times to the present. Many artefacts linked with miners’ lives over genrations are displayed, together with collections of fossils and minerals. The electricity generating plant by Siemens can still be seen as can the machinery used for crushing the ore.