"Unforgettable" by Nat King Cole is a timeless classic that was originally recorded in the key of B major. This iconic song was written by Irving Gordon in 1951 and became a signature piece for Cole. The smooth and velvety voice of Nat King Cole perfectly complemented the romantic and heartfelt lyrics of the song. Interestingly, "Unforgettable" was first released as the B-side of another single, but it gained more popularity and eventually became one of Cole's most beloved songs. The melody of the song is memorable and captivating, with its elegant piano accompaniment and Cole's impeccable delivery. It has since been covered by numerous artists, solidifying its status as a true gem in the music world.