In this historic moment caught on film (January 7th, 1969), Paul McCartney composes “Get Back” seemingly out of thin air while waiting for John Lennon, who casually joins in a couple minutes later.

 

“Get Back” is a song recorded by the English rock band the Beatles and written by Paul McCartney (though credited to Lennon–McCartney), originally released as a single on 11 April 1969 and credited to “The Beatles with Billy Preston”. A different mix of the song became the closing track of Let It Be (1970), which released just after the group split up. The single version was later issued on the compilation albums 1967–1970, 20 Greatest Hits, Past Masters, and 1.
 
The single reached number one in the United Kingdom, the United States, Ireland, Canada, New Zealand, the Netherlands, Australia, France, West Germany, Mexico, Norway, Switzerland, Austria, and Belgium. It was the Beatles’ only single that credited another artist at their request. “Get Back” was the Beatles’ first single release in true stereo in the US. [source]