Kongsberg (Norwegian pronunciation: [ˈkɔ̂ŋːsbær(ɡ)] ) is a historical mining town and municipality in Buskerud county, Norway. The city is located on the river Numedalslågen at the entrance to the valley of Numedal. Kongsberg has been a centre of silver mining, arms production and forestry for centuries, and is the site of high technology industry including the headquarters of Norway's largest defence contractor Kongsberg Gruppen.

Kongsberg, formerly spelled Konningsberg (lit. "King's Mountain"), was developed as a mining city on the basis of the Kongsberg Silver Mines, founded by and named after King Christian IV of Denmark and Norway in 1624. The king invited German engineers and other specialists from Saxony and the Harz region to help build the mining company. As a mining city, Kongsberg had a distinct urban culture that contrasted with its surroundings, strongly influenced by the traditions of mining communities in Germany and where the German language was extensively used in mining business and for religious services. In the first years nearly half of the city's population were German immigrants, and the majority of the engineers and executives were German immigrants and their descendants well into the 19th century, becoming a distinct social class called mining families that formed the educated social elite of Kongsberg in contrast to the Norwegian farming population; the first Nobel laureate in economics Ragnar Frisch belonged to such a Kongsberg mining family. By the 18th century Kongsberg was Norway's second largest city, second only to Bergen. Kongsberg was one of Norway's two privileged mining cities and thus formed a special mining jurisdiction (Bergstad), and only became part of Buskerud county in 1760. On 1 January 1838, the new national law, creating local governments, made Kongsberg a municipality. The rural municipalities of Ytre Sandsvær and Øvre Sandsvær were merged into the municipality of Kongsberg in 1964. Kongsberg gradually lost importance to other cities in the 19th century, particularly to the rapidly growing capital of Christiania (Oslo).

The Kongsberg Silver Mines closed in 1958 after operating for 334 years and is today a museum and the city's main tourist attraction. Kongsberg remains the site of the Royal Norwegian Mint (Norwegian: Det Norske Myntverket), which mints Norwegian coins and also produces circulating and collectors' coins for other countries. Kongsberg is also the home of Norway's major defence contractor, Kongsberg Gruppen, founded in 1814. Two of its best-known products were the Kongsberg Colt and the Krag–Jørgensen rifle.

Both the University of South-Eastern Norway Kongsberg campus, and Tinius Olsen's school, a combined technical vocational college and secondary school, are located in Kongsberg.

Number of minorities (1st and 2nd generation) in Kongsberg by country of origin in 2017

Ancestry	Number
Poland	336
Lithuania	282
India	217
Sweden	211
Denmark	175
Afghanistan	164
Iraq	160
Iran	136
UK	127
Eritrea	118
Philippines	117
Germany	110

Kongsberg was founded by Danish-Norwegian King Christian IV as a mining community in 1624 after the discovery of silver. In its second year, the town of Kongsberg and the Kongsberg Silver Mines began. According to official records, silver was first discovered by the shepherds children Helga Verp and Jacob Grosvold in the summer of 1623. However, the existence of deposits of precious metals was known previously, as evidenced by indications of earlier silver mining. With the rise of silver mining, Kongsberg became the largest industrial center in Norway before the industrial revolution. At the peak of silver mining in the early eighteenth century, Kongsberg's silver mines and related industries contributed 10% of the Denmark–Norway gross national product.

To develop the Kongsberg Silver Mines, Christian IV hired Germans from the silver mines of Saxony and Harz and brought in Germans from other mines in Norway. The Germans brought their knowledge of mining technology, especially important during the start-up phase. Before 1623, the city was located in the royal territory of Sandsvær.

Four years after the establishment of the Kongsberg Silver Mines, most of the 1,500 workers and officials were still German. Gradually, Norwegians entered the workforce and were hired as supervisors. In 1636, 1,370 Germans and 1,600 Norwegians were employed there. In 1648, there were 1,500 Germans and 2,400 Norwegians working in Kongsberg.

Gunpowder was officially introduced in mining in 1681. Mining in the particularly hard rock of Kongsberg Mountain was energy intensive, so the silver mine continued to develop new technology to reduce production costs. A large artificial dam powered the mine's hoists before electricity was introduced. In 1624, a road from Hokksund to Kongsberg was built to serve the Kongsberg Silver Mines, the most important road built in Norway in the 17th century. In 1665, the road was extended to Kristiansand and Larvik.

By 1683, the mining industry was an important industry of the state. The rapid development of Kongsberg meant that the number of workers in the city had increased significantly by the end of the 17th century. The proportion of Norwegians in the workforce increased, but for a long time, the main staff was dominated by Germans. Kongsberg was almost an outpost of Germany in Norway: the mine had a German name, and the official language was German, only later becoming bilingual (German and Danish). In Kongsberg, the German mountain justice system was also used. Legally, this means that the city was bound by independent regulations, partially separating the mining community from the country's legal system. The Germans brought with them the Knappschaft, a guild-like association of miners that provided including free medical assistance, a pension plan, worker sick leave and a Saturday break. The ring agriculture characteristic of Kongsberg may also have been inspired by the German pattern.

The proceeds from silver mining provided a valuable assistance to the tight finances of Denmark. Denmark–Norway relied heavily on the silver of Kongsberg to support an ongoing war against Sweden. Precious metals also became more and more important in the currency, and to get closer to its source of raw materials, the Royal Mint moved in 1686 from Akershus to Kongsberg. During the Great Northern War in 1716, the city became the main target of Karl XII's foray into Norderhof.

Kongsberg was particularly known for its Kongsberg Silver Mines and their high purity. Kongsberg's ore also contained a certain amount of gold and large amounts of copper, cobalt, lead-zinc and fluorite. Roughly 15,750 tonnes (34,720,000 lb) of silver was extracted between the discovery of the silver ore seams in 1623 and the last year of mining in 1957. The workforce at the Kongsberg silver mine began to increase substantially at the end of the 17th century. In the 1769 census, the mines employed about 4,000 workers. With 8,000 inhabitants in all, the town was the second largest in Norway, after Bergen (and thus larger than today's capital, Oslo).

In Norway's 1749 census, Kongsberg was the most populous town in Eastern Norway. It was granted its royal charter of trade—amounting to official township—in 1802. Following several hard years with reduced silver output from the mines, the war of 1807–1814, and a severe town fire in 1810 where 56 houses on the west side were destroyed, mining was complemented by the government establishing a defense industry in 1814. By 1835, the population had declined to 3,540.

Kongsberg is home to the Royal Norwegian Mint (Norwegian: Det Norske Myntverket), which mints Norwegian coins and also produces circulating and collectors' coins for other countries such as Israel. It was established in 1686, and was renamed from the Royal Norwegian Mint (Norwegian: Den Kongelige Mynt) in 2004 after having been sold to private investors (the Mint of Finland and Norwegian company Samlerhuset) in 2003. Kongsberg is also the site of the Kongsberg School of Mines (Kongsberg Bergseminar), an academic institution for mining technology which operated from 1757 to 1814.

During peaceful times, the defence industry gradually evolved into many other kinds of high tech activities as well, now dominating the town's employment. In 1987, however, the state-owned Kongsberg Weapons Factory (Kongsberg Vaapenfabrikk) suffered a major financial crisis as well as accusations of breaching the CoCom rules by selling sensitive technology to the Soviet bloc. As a result, the company was split into several smaller units and partly sold to private investors. Today, the separate firms thrive as one of Norway's main high-tech industrial clusters, centering on the defence and maritime company Kongsberg Gruppen which is listed on the Oslo Stock Exchange.

On 13 October 2021, a man stabbed multiple people with a bladed weapon, killing five and injuring three. Police subsequently apprehended a suspect whom the Kongsberg police chief later told reporters was a Muslim convert.

The coat-of-arms is from modern times and was designed by Hallvard Trætteberg. They were granted on 25 August 1972. They are based upon the old seal for the city from 1689 which shows the Roman god Janus dressed as an emperor (to represent the king); the sword and the pair of scales represents justice. The colour green represents the forests, silver represents the mountains, and gold represents wealth.

Kongsberg is located at the mouth of the valley Numedal; farther to the South the valley is called Lågendalen.

The neighbouring municipalities of Kongsberg are Flesberg to the north; Øvre Eiker and Hof to the east; Lardal, Siljan, and Skien to the south; and Sauherad and Notodden to the west. Of these, the two first lie in Buskerud county like Kongsberg, while Hof and Lardal lie in Vestfold, and the others lie in Telemark. The town is divided by the river Numedalslågen, which has three waterfalls in the town itself.

Kongsberg has a humid continental climate (Dfb), with late summer and autumn as the wettest season and February – April as the driest season. Kongsberg has warm summers by Norwegian standards; average daily highs in summer are comparable to Oslo. In winter Kongsberg is colder than Oslo, and snow cover on the ground is common. The largest snow depth recorded is 123 cm on 3 March 2006.The all-time high temperature 34.6 °C (94.3 °F) was recorded 19 June 1970, while 10 August 1975 recorded 34.5 °C (94.1 °F). The all-time low −32.5 °C (−26.5 °F) was recorded 3 January 1941. As pr January 2022, all monthly record lows are old, 11 from before 1950. All record highs are from after 1950, 5 of 12 from after 2000 (pr January 2022). Kongsberg has recorded 30 °C (86 °F) as early as 14 May (in 2000). The weather station Kongsberg brannstasjon has recorded since 2003, extremes includes data from Kongsberg II, III and IV.

The main highways are the E134, crossing Kongsberg east to west (and connected to the E18 to Oslo), and Norwegian national road 40 (Riksvei 40), going north to south. The Sørland Line stops at Kongsberg Rail Station, with connection to local and regional bus lines.