Some hit songs were written in a matter of hours, but the opposite is also true. Sometimes musicians need to let a song sit for a while before they can finish it the right way. This has happened on several occasions, when for instance a song was written but didn't quite fit the album the artist was working on, so it was later modified and released.
In this gallery, we look back at some songs that took a long time to complete. Click on to get to know them.