If you are interested in plucked string instruments, you should visit the following places and museums and ask to see their harps/lyres/kanteles (most of which are not part of the public exhibitions, but stored somewhere in the collections)
Denmark:
- Vikingelandsbyen in Albertslund: A small but fine Viking village near Copenhagen, where you can ask to see some replicas of Viking Age musical instruments made by the late instrument maker Viggo Bach Nielsen.
- Danish Music Museum in Copenhagen: It stores a gigantic collection of musical instruments, including a considerable number of harps which were on display until 2010 but now are hidden away in the depository since the museum moved into its new premises.
Finland:
- Museum of Folk Music Instruments in Kaustinen
- Sibelius Museum in Turku (instrument collection)
- Finnish Kantele Museum in Jyväskylä
Norway:
- Cultural history collection of the University Museum in Bergen
- Glomsdal Museum in Elverum
- The Norwegian Folk Museum in Oslo stores, among many other Norwegian folk instruments, two folk harps from Østerdalen and the famous Kravik lyre.
- Ringve Museum in Trondheim
Sweden:
- The probably largest collection of Nordic music instruments is hidden away in a museum in Stockholm, which has changed its name numerous times in the past years and most recently it is called Scenkonstmuseet (Swedish Museum of Performing Arts). Their gigantic instrument collection, including MANY interesting harps and other stuff, is not on on public display but hidden away. However, you can see some photographs of their specimens in the museum database. You will find the presumably oldest Norwegian folk harp there (dated 1681), as well as a number of diatonic harps made by Swedish instrument makers from the 18th century onwards, e.g. royal instrument maker Mathias Petter Kraft (who also made Bellman’s cither) and lots of other gems.