This project, involving a team of musicologists, historians, historians of art, archaeologists and engineers, proposes a global re-examination of the phenomenon of the Saintes-Chapelles in the light of the sonic realities marking the ceremonies that took place inside them on a daily basis, focusing particularly on the music, both monophonic and polyphonic, that marked the passage of time. To this point, scholarly study of these chapels has focused largely on their architectural features and their juxtaposition of political and religious aspirations. This project thus proposes a unique perspective from which to experience the interior of these buildings, all the more fascinating since one of their distinctive characteristics was the fact that they were reserved for the sole pleasure of the royal or princely founders. The foundation in 1248 of the Sainte-Chapelle in Paris by St Louis gave rise to the construction of about twenty Saintes-Chapelles between the fourteenth and sixteenth centuries, of which more than half are still extant. These churches, founded by the kings of France and their offspring to house their most precious relics, are among the most spectacular …