I only have classical music, musicals, and audiobooks in iTunes. Not counting audiobooks or multi-movement compositions ripped as one track then it would be...
Morton Feldman, String Quartet No. 2 (in one unbroken movement), 6:07:07
http://www.mode.com/catalog/112feldman.html
Second is Feldman's Piano and String Quartet recorded by the Kronos Quartet, 1:19:38 (also is one unbroken movement)
Morton Feldman, String Quartet No. 2 (in one unbroken movement), 6:07:07
http://www.mode.com/catalog/112feldman.html
Second is Feldman's Piano and String Quartet recorded by the Kronos Quartet, 1:19:38 (also is one unbroken movement)