This article examines the construction of origin myths existing in the Brazilian museums, especially in the National Museum, and its relation with imaginary collectives that are constituted about Brazil during the Empire. It analyzes the Brazilian museums of nineteen century, its relation with the European museums of the same time, as well as inherent elements to the Brazilian society. It tries demonstrate, the narratives formation in which classical traditions interlace with a romantic vision of the local nature; the emphasis in nature as source of scientific knowledge and, finally, a negligence for passed traditions and a valorization of the narratives guided for future achievements. The maintenance of the devaluation of the past contributes for the legitimation difficulty of the museums that come backed for the preservation of cultural traditions.