The Missa Scala Aretina by Francesc Valls is considered to be one of the most important works of Spanish music history. Written in the polychoral tradition and based on Guido d’Arezzo’s hexachord, and named after him, the work was composed for the cathedral of Barcelona, possibly to celebrate the closing of the Catalonian Parliament in January 1702. It owes its fame to the heated controversy over aesthetics which arose as a result of one of its passages. At one point the controversy involved over 50 musicians including Alessandro Scarlatti, and against the political backdrop of the Spanish War of Succession (1700-1714). La Grande Chapelle tackles the fascinating challenge of rediscovering this unique work in its original setting and presents us with a number of excellent unpublished pieces from Valls’ huge musical production.