The Danish Music Museum in Copenhagen is one of the oldest museums of musical history in the world, having been founded in 1898. It features detailed exhibitions on the chronological development of musical instruments from the Bronze Age to the 21st century.
Although I can’t recall seeing any instruments from the Bronze Age (which was four to five thousand years ago), I do remember numerous instruments from later centuries, particularly the 17th, 18th and 19th.
The museum has a great variety of pianos and other keyboard instruments, such as harpsichords, clavichords and pianofortes.
From the early 20th century, they even have some player pianos with piano rolls. The piano roll was a roll of strong paper with holes to record the notes. (Holes punched in paper rolls or in cards were a commonly used form of data storage for all sorts of purposes until well into the 1970s.)
These player pianos were completely mechanical, and were often used in houses that had no electricity. Energy was provided by someone pumping the foot-pedals, enabling the piano to play itself.
(See also: Look ma, no electrons!)
There were also thematic exhibitions, for instance this one on how violins are made. And there were numerous examples of violins and other stringed instruments from the past several centuries.
Another exhibit was arranged to show how musical notation has changed through the centuries.
When I was there (I went on my bike on a very rainy day), the Danish Music Museum was still in its old building at Åbenrå 30.
A few years later, in 2014, the museum moved into larger quarters in the former Radio House at Rosenørns Allé 22 in Frederiksberg. There they have more space for their many exhibits, and for their library and educational activities. Also, they have started a new initiative called “The Sound Room”, where “children of all ages can have a try at playing everything from the harp and the kettledrum to the electrical guitar and the xylophone.”
My photos in this post are from 2009. I revised the text in 2020.