The longest song ever recorded is over 6 hours long - Apparently.
The song "Longplayer" by Jem Finer was started on January 1, 2000, and is designed to continue playing without repetition until December 31, 2999. This self-sustaining piece of music is based on a complex algorithm that generates new sounds based on a series of mathematical formulas. The song has been playing continuously since its inception, with a small team responsible for maintaining the equipment and software that powers it.