The clock strikes seven in the morning. Inside the baroque St. Stephen’s Cathedral, in the heart of the Bavarian city of Passau, the absolute silence feels almost solid. The dawn light is just beginning to pierce through the stained-glass windows. For most, this is a place of worship and architectural awe. For the Orgelbauer, the organ builder and restorer, it is his office. An office that extends many meters high, hidden behind scaffoldings, labyrinths of cables, and thousands of pipes of metal and wood.

© Maria-Anna Akrida

The life of this technician is a unique, almost ascetic routine. Often, the most critical tasks, such as tuning, require working for endless hours in the absolute solitude of an empty cathedral, sometimes even deep into the night when the city is asleep. There, among the shadows of the vaults, the Orgelbauer becomes the link between heavy manual labor and high art. He must possess a devout patience to inspect thousands of tiny components, the knowledge of an experienced carpenter and metalsmith, and the trained ear of a musician. He is a man who lives in obscurity, hidden within the “bowels” of the instrument, yet carrying the immense responsibility for the organ’s final sonic result. From the largest pipe, measuring ten meters in height, down to the smallest one, just a few millimeters long, every single one is meticulously checked, one by one.

To write about the pipe organ of Passau is like trying to describe a living mythical giant. When completed, it will be the largest church organ in the world. To grasp its scale, a comparison with Greek standards is enough: the largest organ in Greece, the majestic pipe organ in the “Christos Lambrakis Hall” of the Athens Megaron Concert Hall, which fills us with awe with its 6,082 pipes and 76 registers, is barely… one-quarter of the German beast. Although different in size, these two instruments share the title of the largest organ in their respective countries, and both were built by the renowned German company “Klais Orgelbau.”

What is the design and construction process of a pipe organ actually like? What do the Orgelbauers need to take into account regarding space, acoustics, and materials? I spoke with the people at “Klais” to solve all these fascinating questions:

The space where the organ will be installed is the most important criterion for its design. Organs destined for cathedrals have significant differences from those that will remain in concert halls. Cathedral organs usually need to follow the aesthetics, history, and acoustics of the space to ‘blend in’ with the scenery. The reverberation of cathedrals must also be taken into account, as opposed to the more controlled and ‘dry’ acoustics of a concert hall.

Beyond acoustics, the choice of materials plays a massive role, as a delicate science hides behind every pipe. To produce different tonal colors, the Orgelbauer use special alloys of tin and lead for the metal pipes, as well as choice woods, such as pear, oak, or spruce, for the lower, warmer frequencies.

© Maria-Anna Akrida

This entire variety of materials and sounds reaches its peak in the case of Passau. Following its radical renovation, the instrument will consist of 11,587 pipes and 174 registers in the main organ alone, whose 1731 baroque facade dominates the back of the cathedral. When the inside of the instrument was renovated in 1928, the late-romantic beast briefly held the title of the largest organ in the entire world. Together with the other five organs scattered throughout, left and right at the back, near the altar, and in the side galleries, the overall architecture is captivating.

The most magical detail, however, is hidden in the sixth and final instrument: the so-called Fernorgel (echo organ), which is concealed inside the cathedral’s breathtaking ceiling. Its sound diffuses into the space through a hidden opening in the roof, making the listener feel as though the music is descending directly from heaven. This is an enterprise that requires precise coordination from the Orgelbauer, due to the distance the sound must travel.

In total, the renovated colossus will amount to roughly 22.536 pipes with over 276 registers, all to be controlled from a single console. The reconstruction of the οrgan is expected to be completed in the summer of 2027, when a concert of corresponding caliber will surely take place, as fits such a monument of world musical heritage.

Until the first official note is heard, the invisible work of the builders continues far from the spotlight, inside the silence of the cathedral. Thanks to their precise work and patience, this historic colossus is not just a monument of the past, but a living organism breathing once again. The people behind the giants are completing their work, and all that is left now, is to let the music speak.