Thom Yorke of Radiohead recently put together a piece of music for his artist friend Stanley Donwood, the guy responsible for a lot of Radiohead’s artwork. This was for a music exhibit in Australia. Thom’s soundtrack to the exhibit ran for 432 hours—that’s about 18 days—without repeating. That has to be the longest song ever written, right? Nope. The avant garde composer John Cage wrote a piece for the organ called “As Slow As Possible.” A performance of this piece began at St Burchardi Church in Halberstadt, Germany, in 2001. The instructions say that the piece needs to last 639 years. It won’t wrap up until sometime in the year 2640. And then there’s still the extended dance mix.