In the early and mid-70s an unusual creative explosion took place in Barcelona, which meant the first manifestation of avant-garde experimental rock known in Spanish territory. Starting from free jazz, through punk and industrial music, and reaching electronics, several generations of snipers would take charge of consolidating a tradition that, consolidated in the 80s, still survives today. Born in the underground and taking over from Barcelona's progressive rock from 1969-73, it was also the first known independent rock manifestation at the national level, as evidenced by the fact that Macromassa self-released their first album in 1978 and the appearance of other labels independents in Barcelona prior to the Movida madrileña. Too and too soon, all these ruptures took their toll on a movement that was not such and that had more repercussion in France or the United States than in Spain. The risky and minority of their proposals, the hermetic and self-sufficient character of some bands that did not pursue popular recognition, the institutional disinterest and the disaffection of a public that was allowed to be carried away by the escapist sounds of the Transition and the layetano-salsa monopoly of Zeleste, condemned to marginalization that period that continues to be ignored by the official chronicles despite being the most creative and transgressive of events in the recent cultural heritage of the city of Barcelona. La Ciudad Secreta, a choral portrait in which many of its protagonists are interviewed, drawing in unison an analysis of the political and social degradation of Barcelona in the period between the pre-Transition and the Olympics, aims to restore identity and entity to a stimulating stage that musically can be compared to phenomena such as Krautrock in Germany, Canterbury in England and the French avant rock scene, generating its own circuit, closely linked to the culture of fanzines, free radios and cassettes. Immersing yourself in the pages and sounds of this adventure, the reader will experience the same emotion.