In C is a landmark work by US composer Terry Riley. Over the course of an hour or so, simple melodies intertwine, creating a cloud of sound. Each musician plays independently, changing melodies as he or she sees fit, while listening carefully to what the others are playing. Each In C performance is therefore unique.

This version in the ARCOOP building is particularly unique: the numerous musicians occupy all five floors of the building, which is illuminated. The audience is seated downstairs, in a space designed and organized by architect Karel Klomp. And to make the most of the lounge, the Blue Oyster Laser Bar unveils a series of cocktails.