Bull of Heaven makes really long songs. Their longest completed song is called "Like a Wall in Which an Insect Lives and Gnaws." It's a 5.7 year song. Yeah, that's right. Granted, it may not be as long as the song Longplayer, which will be completed in the year 2999, nor is it as long John Cage's "Organ²/ASLP," which is currently being recorded and is scheduled to last over 6000 years, and of course neither of the songs mentioned can shake a stick at Ian D. Mellish's "Olitsky," a loop intended to last 1.6 million years. However, keep in mind that these songs are all still being made (and won't be completed for quite some time,) so Bull of Heaven's "Plucked for the Breast of the Dead" holds the current record for longest song in the world, and will continue to carry that distinction for millennia to come.
However, even Ian D Mellish's "Olitsky" pales in comparison to Bull of Heaven's longest piece in production. This song is called 260: lcm(2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83). This song will be over 8 SEXTILLION years long, or to be more precise 8,462,937,602,125,701,219,674,955.2362595095 years long. To put this into perspective, the universe is 13.8 billion years old. If yous started listening to this song since the Big Bang, you'd not even make it through 1/600000000000000 of the song. Let that sink in.