The longest piece of music ever composed is being performed right now in a church in Germany — a piece designed to last 639 years, played on a special organ that holds each note for months or years at a time — and the performance, which began in 2001, is not expected to end until the year 2640

In the former Cistercian convent church of St. Burchardi, in the small town of Halberstadt in the German state of Saxony-Anhalt, a single sustained chord has been ringing through the stone interior since the afternoon of 5 February 2024. The chord is held by a wooden-framed, custom-built mechanical organ on a raised wooden platform at the centre of the church. Its bellows are electric, powered by a small generator on standby, and the compressed air is carried to the organ through a pipe that runs underground from the bellows platform to the instrument itself. The chord that has been sounding since February 2024 consists of seven notes. It will continue to sound until 5 August 2026, at which point a small group of volunteer organists, supervised by Rainer Neugebauer of the John Cage Organ Foundation, will manually add or remove organ pipes to change the chord to whatever the score specifies next. The chord change will be the 17th since the piece began.

The piece is John Cage’s ORGAN²/ASLSP, an eight-page organ composition that Cage wrote in 1987 as an adaptation of his 1985 piano piece ASLSP. According to the John Cage Organ Project’s official documentation of the Halberstadt performance, the piece title abbreviates the instruction “As SLow aS Possible,” a phrase Cage took from the closing pages of James Joyce’s Finnegans Wake. A normal performance of ORGAN²/ASLSP, in any conventional concert setting, lasts between twenty minutes and an hour. The piece consists of eight pages of relatively simple musical notation, with held chords and rests interspersed in a pattern designed to test what “slowly” can mean. The Halberstadt performance is, by an enormous margin, the slowest interpretation that has ever been attempted of any musical work.

How the 639-year duration was chosen

The duration of 639 years was not specified by Cage himself. According to NPR’s 2024 coverage of the most recent chord change at Halberstadt, the figure was arrived at by a group of German musicians, philosophers, and theologians who, in the years after Cage’s death in 1992, debated how the instruction “as slowly as possible” might be interpreted in its most rigorous extreme form. The group settled on the year 1361, the year in which the world’s first 12-tone Gothic organ (an instrument with a keyboard arrangement similar to the modern one) was installed at Halberstadt Cathedral. The interval between that historical moment and the dawn of the new millennium in 2000 was 639 years. The group reasoned that 639 years was therefore a duration with both local historical resonance and a clean symbolic structure. The performance was scheduled to begin on 5 September 2001, the 89th birthday of John Cage, who had died in 1992 at the age of 79.

The first 18 months of the performance, from September 2001 to February 2003, consisted entirely of silence. Cage’s score begins with a rest, and in a performance designed to last 639 years, even a brief rest is scaled to a duration that exceeds human attention spans. The first audible notes of the piece did not sound until 5 February 2003, when the initial chord — G-sharp and B — was struck and held. Visitors who came to the church during the first year and a half of the performance heard only the wheezing of the bellows on the platform, not the organ itself. The musical performance, in its proper sense, had not yet begun.

The organ itself

The instrument that is performing the piece is being built in stages, with new pipes added or removed as the score requires. Its current configuration includes the seven pipes corresponding to the chord that has been held since February 2024. Earlier configurations have included anywhere from one to six pipes. The mechanism is purely mechanical — weights hold the keys down in their assigned positions for the duration of each held chord, with the wind supply coming continuously from the electric bellows. The longest single sustained chord in the performance so far ran from October 2013 to September 2020, a continuous seven years of the same combination of pitches resonating through the stone walls of the church. The 5 September 2020 chord change was attended by a worldwide media audience, including coverage from Rolling Stone, the BBC, and most major European newspapers, as the church readmitted visitors after the early phase of the COVID-19 pandemic.

The acoustics of the St. Burchardi church, a stone structure dating to 1208, contribute substantially to the character of the performance. The held chords resonate in the space for several seconds after the wind to the pipes is cut, and the slow decay of each chord is part of what visitors experience when they sit in the church and listen. The Cage organ itself, although less ancient than the church around it, is now part of a building that has been continuously in use for more than 800 years. By the time the performance ends in 2640, the building will have been continuously in use for more than 1,400 years, and the Halberstadt performance will have spanned roughly 45 percent of that total existence.

What the piece is asking

The philosophical significance of the Halberstadt performance has been debated within Cage scholarship since the project was first announced in the late 1990s. According to a 2024 reflection by the musicologist Kyle Gann published in The Conversation, Gann was initially sceptical of the project, dismissing it in his 2012 book on Cage as “a poor use of human and environmental resources” and “more of a gimmick than a real piece of music.” Gann subsequently revised his view after a conversation with Laura Kuhn, the executive director of the John Cage Trust, in which Kuhn argued that the Halberstadt project genuinely realises something Cage himself implied in his music — that any musical event can in principle expand to fill any temporal frame, including frames much larger than a human lifespan.

The implicit invitation of the Halberstadt performance is to experience music on a timescale that is essentially impossible for any individual listener to fully apprehend. No one will ever hear the piece from beginning to end. Generations of audiences will sit in the church and hear, perhaps, one chord during a single visit, perhaps one chord change every decade or so if they are local residents. The composer is dead. The original planners of the 639-year duration will all be dead long before the piece ends. The visitors who attend the 2026 chord change will be dead before perhaps a third of the remaining chord changes take place. The piece exists, in its complete form, only as a conceptual object. The physical performance is a multi-generational project that no human being will ever fully witness from inside their own lifespan.

The longer perspective

According to the Wikipedia reference on As Slow as Possible, the Halberstadt performance is the longest non-computerised musical performance currently in progress anywhere in the world, but it is not strictly the longest musical performance currently underway in absolute terms. That distinction belongs to Longplayer, a 1,000-year computerised composition by the British musician Jem Finer that began at the start of the year 2000 and is scheduled to end at the start of the year 3000. Longplayer uses computer algorithms to generate continuous music from a 20-minute source recording of Tibetan singing bowls, with the algorithm cycling through variations such that the same musical moment will not recur within the entire 1,000-year duration. The Halberstadt performance, in contrast, is fully mechanical, runs from a fixed score, and involves regular human attendance to change pipes at scheduled moments. The two projects are different in character, but together they represent the current state of human attempts to extend music meaningfully beyond a single lifespan.

The next chord change at Halberstadt is scheduled for 5 August 2026. The change after that is currently unscheduled and will depend on the score’s instructions and the continued operation of the John Cage Organ Foundation that maintains the performance. The bellows generator, the underground air pipe, the wooden organ frame, and the modest stone church around them are all under the care of an institution whose continued existence is itself, on a 639-year timescale, far from guaranteed. The piece’s success in reaching the year 2640 will depend on roughly 25 successive generations of Halberstadt residents continuing to fund, maintain, and care for an organ playing one of the slowest sequences of musical decisions ever attempted by human beings. The first 23 years of the performance have gone, by every public measure, more or less as planned. The remaining 616 years are still ahead.