Røros (Plaassja, ) is a municipality in Trøndelag county, Norway. The administrative centre of the municipality is the town of Røros. Some of the villages in Røros include Brekken, Glåmos, Feragen, Galåa, and Hitterdalen. The mining town of Røros (the administrative centre of the municipality) is sometimes called Bergstaden which means "mountain town" due to its historical notoriety for copper mining. It is one of two towns in Norway that were historically designated "mining towns", along with the "silver-town" of Kongsberg. The modern-day inhabitants of Røros still work and live in the characteristic 17th and 18th century buildings which led to its designation as a UNESCO World Heritage Site in 1980. Røros has about 80 wooden houses, most of them standing around courtyards. Many retain their dark pitch-log facades, giving the town a medieval appearance. The municipality is the 39th largest by area out of the 356 municipalities in Norway. Røros is the 169th most populous municipality in Norway with a population of 5,572. The municipality's population density is and its population has decreased by 0.6% over the previous 10-year period. The parish of Røros was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). On 1 January 1875, an unpopulated area of the neighbouring municipality of Ålen was transferred to Røros. On 1 January 1926, Røros was split into four municipalities: Røros landsogn (population: 701), Brekken (population: 1,098), Glåmos (population: 983), and the town of Røros (population: 2,284). During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, the four municipalities of Glåmos (population: 700), Brekken (population: 964), Røros landsogn (population: 482), and the town of Røros (population: 3,063) were all reunited under the name Røros. On 21 April 1989, an unpopulated part of Røros was transferred to the neighbouring Holtålen municipality. On 1 January 2018, the municipality switched from the old Sør-Trøndelag county to the new Trøndelag county.