A extremely long music composition had a big moment recently when it changed chord for the first time in two years.

The composition by experimental and avant-garde composer John Cage, titled As Slow As Possible, began in 2001. The eight-part composition is being played on a specially built organ housed in a church in Germany.

According to the BBC, volunteers added another pipe to the mechanical organ in order to create the new sound.

The adjustment on February 6 marked the 16th chord change for As Slow As Possible, which will not conclude until 2640. It began with a slow start: after 18 months of silence, the first notes only sounded in 2003.

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The next scheduled chord change will take place on August 5, 2026, according to the website for the John Cage Organ Art Project.

The BBC also reported that some attendees of the chord change booked their tickets years in advance, in order to see it in person at the Burchardi Church in the German town of Halberstadt.

Cage never specified the tempo of the composition, only the pitch and duration of the sounds. When As Slow As Possible premiered in 1987, the performance was just under 30 minutes. But a performance in 2009 lasted nearly 15 hours.

Cage, who died in 1992, is considered a key influence on art of the postwar era. His 1952 piece 4’33”, a composition that calls for its performers to remain silent for the duration of its title, is widely viewed as one of the most important experimental works of its kind.