Traces of public spaces in transforming city walls: The case of Selani̇k-İstanbul

In the history and memory of the city, city walls have formed the form and physical structure of the urban fabric as well as the protection function by surrounding the city. City walls were formed with the foundation of the city and according to Kostof's etymological explanation; "city" and "wall" are synonymous and identical. Thus, the forms of cities are formed by the walls surrounding them, and the city and the wall bring each other into existence. The city walls, which are considered to have become dysfunctional with the modernisation period, have been demolished in many cities around the world, and the large gaps created by the demolished walls have provided an opportunity for the formation of public space for the changing urban life. The main fiction and problematic of the thesis study has developed around determining the roles of city walls in the formation of today's public spaces, searching the traces of the "formation of modern public spaces" in the "gaps left behind by city walls" and how these formations have caused formations in the changing urban texture and changing urban life. In the structure created in this direction; three main concepts; "border", "gap" and "threshold" concepts are analysed through the urban texture in order to create the theoretical infrastructure of the subject. The starting point of these three concepts was formed in parallel with the subject of the study, which is the transformation of city walls into public spaces. City walls create the concept of border with its physical line, public spaces create the concept of space with its physical dimension and threshold formation occurs at the point where these transform into each other. After the theoretical background, the cities of Vienna, Kraków and Nicosia were analysed in order to see the equivalents of the destruction of walls and their transformation into public spaces in other cities around the world. In order to examine the spatial reflection of the subject of the study; the 19th and 20th century modenisation and Tanzimat Period, which is the period when the walls were demolished and the cities were expanded and re-planned, was selected, and a field study was created within the framework of conceptual topics through the cities of Thessaloniki and Istanbul, two important cities of the Ottoman Empire in this period. These two cities were chosen due to the similarities in the way the cities developed, the interventions made and the re-planning works carried out by two French architects. The Galata District in Istanbul was taken into consideration due to its similar ethnic structure with Thessaloniki and the similarity of the transformation story of its walls. In both cities, land walls were demolished and transformed into streets and boulevards with intensive public use, while sea walls were transformed into coastal promenades. It has been analysed that in some parts of the city where the walls could not be transformed and remained as ruins, urban stratification and intermediate spaces, urban ruptures and urban traumas occurred. As a method; it is aimed to read the change of the social identity of the city with "postcards", one of the inventions of the modernisation period, the source of memory and information of the period, and the change of the physical identity of the city with "maps". As a result of the analyses, researches and determinations made, city walls today can be read in three classifications as walls that can continue their physical existence by being taken under protection, walls that can continue their existence in the trace of their disappearance and walls that remain among the city parts in the form of ruins. Keywords: Ottoman modernisation, 19th and 20th century urban planning practices, city walls, public spaces, urban boundary, urban gap, urban threshold.