This article focuses on one of the most suggestive proposals within the sound domain of the twentieth century: the concerts for bells and bell towers devised by the Spanish musician Llorenç Barber. His original idea of transforming the city into a monumental instrument provides the starting point for the analysis. In order to access the competing claims of sound art versus music, the text approaches Barber’s creative thinking as if it were a sound grammar devised specifically for the city: materials and performance techniques become a ‘phonetics’, structural elements as a ‘morphology’, the ‘syntax’ of sound-handling strategies, and the formal structure of the score as a ‘narrative’ of the concert. Within each dimension, the text shows how the ‘city instrument’ has extended Barber’s creative horizon by transforming musical problems into unclassifiable strategies of dealing with sound, which are capable of producing a sonic experience deeply rooted in the historical and cultural development of the city. Finally, this research shows how uncertainty, indeterminacy, ambiguity, accident or change (unacceptable concepts for the traditional musical domain) become an essential part of these works. Inevitably, such aspects require from the ‘composer’ a kind of pragmatism that seems to be inherent in the outdoor sound design.