The original pipes of the Bethlehem organ are emitting sound once again. Mounted on a small portable bellows, their thousand-year-old voices resonate for the first time in modern times. It is a unique window to the past, allowing us to listen directly to a medieval musical sound: we can perceive the very same sound that adorned the liturgy of the Basilica of the Nativity in the time of the Crusaders. One of the project’s lines of work is precisely to present, analyse, understand, and revive the sound experience of a legendary instrument that seemed condemned to eternal silence.
Another finding has been the discovery that the geometry of the original pipes conforms with millimetric precision to the mathematical models described in theoretical treatises from the 10th and 11th centuries. These treatises describe how to build an instrument according to the numerical proportions that govern the Divine Creation. While the Scriptures state that God created a harmonious cosmos “by measure, number, and weight” (Wisdom 11:20), medieval scholars sought to elucidate how universal harmonic proportions are manifested in organ pipes. The task represented a significant challenge, given the acoustic complexity of open pipes. However, the Bethlehem organ demonstrates that medieval cosmologists and artisans succeeded in reconciling theory and practice. The organ ceased to be a simple liturgical ornament and became a symbol of cosmic creation: it reflected the harmony of the “music of the spheres,” making it tangible and perceptible to the human soul.
Each pipe of the Bethlehem organ holds the fascinating story of those who built, tuned, used, transported it to the Holy Land, and finally dismantled it to hide it underground, thereby protecting it from devastation in the face of an imminent Muslim invasion. To decipher this history, researchers have taken samples that are being analysed in laboratories using the most cutting-edge technology. Alloys, traces of solder, organic remains, tool marks, guide marks engraved by the organ builder himself… every trace allows us to reconstruct the manufacturing process, the materials used, and the technical and theoretical knowledge that medieval artisans possessed.
Among the 222 preserved pipes, there are examples from all the original ranks. With these as a guide, the international team of experts is working on replicating the original pipes and reconstructing the lost parts of the instrument, so that the organ’s sound can be recovered in all its fullness. The extraordinary preservation of the material—still capable of producing sound in some cases—makes it possible to compare the timbre of the original pipes with that of the experimental replicas. The reconstructed instrument, still in a pilot phase, will not only allow us to listen to it but also to play it, explore its musical possibilities… and, above all, to bring it back to life.
The project also explores the political and liturgical context of the organ within the Basilica of the Nativity, especially concerning the cultural transfers between West and East during the era of the Crusades. While most of the Latin clergy of Jerusalem-Bethlehem came from Paris and northern France, the liturgy adopted customs from the dioceses of Chartres, Rouen, and York. The project seeks to clarify the organ’s place within this fascinating amalgam of influences. Furthermore, a collaborative effort will create a digital reconstruction of the interior of the Basilica of the Nativity to explore the organ’s probable original location, its visual impact, and its acoustic effect within the architectural space.
Medieval iconography often depicts the organ accompanied by a set of tuned bells hanging in a row to one side or above it. The pipes of the Bethlehem organ were buried along with eleven tuned bells, four of which show the names of the notes with letters marked on the bells themselves. Were these bells intended to sound together with the organ? The project is also investigating these bells to produce exact replicas and thus study their sonic properties, with the ultimate goal of clarifying the possible musical connection between the organ and the bells.
The Bethlehem Organ project is being developed in close collaboration with the Terra Sancta Museum and the Custody of the Holy Land, the institution that manages it. Our work is thus part of a history of preservation that dates back more than 800 years, when St. Francis of Assisi inspired the Franciscan mission to protect the Holy Places.
The Custody has been the guardian of countless archaeological and artistic treasures, including the remains of this unique organ. The Terra Sancta Museum is the culmination of this work: a world-renowned centre dedicated to showcasing the historical and cultural richness of Christianity in Jerusalem.
Our research contributes directly to the museum’s vision. The reconstructed organ will occupy a place of honour in the future music room, a space designed to revive the sound heritage of the Holy Land. In this way, our project not only recovers a medieval sound but also becomes a new chapter in the long and admirable history of the Custody, ensuring that the echo of the faith and culture of the Crusaders resonates for future generations.