Continuity and discontinuity in the urban form

Methods of urban morphology offer an opportunity to develop holistic approaches to sustaining heritage cities, which address local cultures and identities, through an analysis of the evolution of the place and its interpretation in spatial and architectural practices. Particularly, the dialectical relationships of elements of urban form on different scales or instances of the same element can be investigated. For example, the structure of plots is a result of the sequence of transformations, description of the history of the part of territory: multi-level diagrams with a representation of the chronological sequence of structural development could be a key to the logic of a dynamic process, even when the urban fabric presents an orthogonal grid. In fact, in these cases, we can recognize the process of transformation of the urban fabric throughout the hierarchically produced order between the roads that have come to be determined over time (readable in the arrangement of the entrances of the buildings, in the distribution of commercial activities, the height of building and largeness of the street). However, there is a difficulty in finding the key specificities of a particular piece of urban fabric, especially for specialists who investigate their indigenous environments (which they take for granted), at the stage of familiarization with the method. The paper illustrates the evidential efficiency of the comparative method, presenting the intermediate results of the ongoing comparative morphological case study of the development of an urban form of colonial cities Krasnoyarsk (Siberia, Russia) and Quebec (Canada), which were both established in the 17th century in a similar climate, and have clear morphological similarities and evident differences. The first could speak about objective features inherent in the construction of cities, regardless of the socio-political and economic context, the second can indicate the unique specificities that are most characteristic of the place under consideration