This paper reflects on some of the pressures involved in researching the documentation kept by the Canadian firm ‘Brazilian Traction, Light and Power Company,’ better known in Brazil simply as ‘Light’. It is well known that Light held monopoliesfor some of the principle urban networks in the Rio de Janeiro- São Paulo axis, and that the company played a leading role in transforming urban eenvironments, affecting population mobility, and expanding development vectors in Brazil’s largest cities during the first half of the twentieth century. Beyond the strong ties that link the urban domain to the history of public utility companies, what effects can archival turning have on the questions presented in this article, as well as on the ways in which we conduct and present research on cities? Addressing the materiality of physical archives while experimenting the city, and vice versa, the fragments presented in thisarticle rehearse a wayof articulating thearchive that reflects onthe state and the city, while also articulating certain forms of violence: promises of conservation; threats of destruction; efforts of remembering and forgetting; and forms of access, authorization and insistence.