The Sibelius Museum is one of the few museums in the world dedicated to a single composer. The collection covers Jean Sibelius's life and career through manuscripts, instruments, and personal effects, and also holds around 300 historical instruments from across Europe. The building itself is a striking piece of 1960s brutalist architecture by Woldemar Baeckman, designed so that its concrete forms echo the acoustics of music.
There's a small concert hall used for chamber music events throughout the year — check the schedule at the entrance. The museum sits on the edge of the Abo Akademi campus, a short walk from the cathedral.