The Halberstadt organ is a historic pipe organ located in the St. Burchardi Church in Halberstadt, Germany. It was built in 1361 and is one of the oldest playable organs in the world. The organ features a unique design with multiple manuals and a wide range of pipes, allowing for a rich variety of sounds. In 1987, a long-term performance of John Cage's composition "As Slow As Possible" began, which is set to last 639 years. This performance highlights the organ's significance in both music history and contemporary art, drawing attention to the relationship between time and sound.