Really fun music museum. For 5 euros you get to see and hear the world's largest collection of musical instruments. The admission fee comes with a headset that plays a piece of music when you walk up to instruments so you don't just see them, you hear them too. Some really bizarre instruments to see as well including 7 foot high pianos, dragon shaped brass instruments and some crazy mechanical instruments from the 1800's. Well worth an afternoon.
Very close to the Royal Palace is this beautiful music museum. It has more than 8000 instruments, but only 1500 are on display. The variety of instruments is surprising and the audio guide that they give you with the entrance is very good to listen to the sound of many of them. The building where the museum works draws attention, because it has a modernist style, different from the surrounding buildings. The value of the ticket in 2018 is 8 euros and the museum closes at 4:45 p.m. (the same, it is always good to confirm this information). There is a terrace from where you have beautiful views of the city.