The Johnny Cash Museum, on 3rd Avenue South just off Broadway, is a privately run, very densely packed shrine to the Man in Black. The collection — handwritten lyrics, stage outfits, guitars, the cell-door panel from Folsom State Prison, family Bibles, the famous black wedding suit — is one of the most personal of any country-music museum. Several listening stations let you choose tracks across his career.
Allow two hours. The museum is a few blocks from the Country Music Hall of Fame and pairs neatly with it; a separate Patsy Cline Museum sits upstairs in the same building and is included in the combined ticket. Lines are long on weekends; book online to skip them.