The present article analyzes the formation of the collections of the Historical Museum of the City of Rio de Janeiro, and its relation with the urban reforms that occurred in the former capital of the Republic. The successive interferences in the city created an extremely fragmented collection. The objects that compose it, in its majority, had not gone to the museum due to a desire to collect. Based on available documentation in the archives and on the testimony of several people who participated in the process, we analyzed the formation of the collections with the intention of identifying the existence of a museological project defined by the institution. Different objects from different periods had become witnesses of the movements that took place in Rio de Janeiro. Public spaces, governmental, religious and particular buildings, all had been affected by the transformation of the city. When removed from the urbs and taken to the museum, the property that became part of the collection lost its aesthetic, decorative, economic value, and value of use, and now have only the value of testimony. The excessive fragmentation of the collections its representation in relation to the city.