Borders affect both spatial properties and human behaviors. The way people experience spaces determines the thickness of borders, and the thickness is the space of threshold. This architectural concept is inspired by the architectural elements – door which involves a character of connection and separation. The duality of interface challenges the usages and the status of surroundings at different moments. Thus, the research is about how do the thresholds as an architectural concept mediate the spatial properties and people’s movement?

In contemporary cities, there is a way that the constructed buildings allow possibilities to renovate and re-use instead of building a new one in an empty plot. The courtyards are surrounded by the standard apartments which were the results of economic-oriented policy in Russia. They represent self-built lifestyles in the center of the blocks. However, the city is bound to face the issue of demolition because of planning. The site of the project is one of the common blocks in Yekaterinburg which is a grid city with some generic spatial types. The pedestrian streets and the driveways follow the regular grids and affect the way of movement of people.

The manifesto of the city is called The Door City, it conveys the future city will be a city with some small territories which are closer to the living and walking dimension. The project aims to use a topological way, providing a relation of transformation which can be applied to the grids, the courtyards, and the apartments, in Yekaterinburg. Based on the relation, the small territories can be explored into various spatial programs. Thus, the walking routes are generated by the links of the distributed territories, and all involve the ambiance of a dual property. These spaces of the levels of publicness promote diversity, displaying the behaviors without a clear boundary; also function as a blank for the inhabitants to arrange their courtyard. The project concludes with a reflection and a new insight, giving the city another walking culture and transformation on the community scale.