This paper is focused on two main topics which influence the contemporary and on-going debate about museums (and, among others, city museums): the existence of a collection and of a building dedicated to housing it. Then it deals with the question of the size of cities selected for the establishment of a city museum (large or small centres). Finally, the use of documentary, iconographical, cartographical sources and multimedia tools for the representation of urban changes over a long period of time is considered from the point of view of the necessity to communicate with a broad range of users (for example, tourists, citizens, new immigrants, children).