John Cage’s piece Organ²/ASLSP (As SLow aS Possible), adapted from his original piano composition in 1985 for the organ in 1987, is currently the longest performance piece ever attempted: it is expected to take 639 years to finish, begun on Sept 5, 2001 (John Cage’s birthday) and running until the year 2640.
An organ was specifically built for the endeavor, which resides in the St. Buchardi Church in Halberstadt, Germany. The duration and location were chosen specifically, as “the first modern organ, the Blokwerk organ, was built for the Halberstadt Cathedral in 1361, 639 years before the turn of the millennium.” [ 2 ] Since the original remains operative, there is hope that the ASLSP organ will last just as long in order complete its performance.
How many notes have been played so far? On October 5th, 2013, at 4:00 p.m., the 13th note change took place. There won’t be another change in the hyperdurational sounding for seven more years.
For more on John Cage, see A Vexing Composition.