The Museum of Norwegian Folk Art is one of the museums you could/should definitely visit on your way around southern Norway. It is mainly devoted to the history and production of Hardanger violins (you may also know them as Jástad violins). Their origins can be dated back to the beginning of the 16th century. century, the first classical ones were created in 1651 by Ole Jonsen Jaastad and are now Norway’s national instrument.
Unlike classical violins, they have a second set of strings, which are not played, but which are sounded by resonance, as well as colourful decoration, most often with carvings and mother-of-pearl.
Last but not least, the museum is in a beautiful wooden house.