The soundtrack to a video commemorating the 35th anniversary of Elvis' death, this is essentially a reissue of the sweetly sentimental country ballad from his self-titled 1956 debut – until just past the halfway point, when his daughter's harmonies float in. Lisa Marie starts out tentative, almost sheepish. But the emotional communion of it settles in, and just like Natalie and Nat King Cole's "Unforgettable," it becomes a legit tear-jerker.

“Youth Knows No Pain”

“Like on 'Youth Knows No Pain' — we are the ones that should demonstrate, because we can take it,” Likke Li said. “We can pierce ourselves, take Ecstasy, dance all night and still go to work at our McDonald's jobs.” Despite the hedonistic sentiment in the song, the Swedish singer also admitted in hindsight her youth had repercussions. “I remember when I was 18-19 and feeling that I know it all,” Li said. “I always feel that I know it all. But that song is about realizing you don’t, and reflecting, ‘Boy, if I only knew what would follow.’”