GENTRIFICATION AS RESIDENTIAL EXISTING PATRIMONY CONSERVATION STRATEGY

CITIES THROUGH TIME

Cities experience so many transformations during thè time, which change them and affect their appearance in both positive and negative aspects, e.g. physically, socially, economically, and culturally, etc. City, in any period of time, is the result of overlaying of different factors which have led to thè changes in past and made up thè current faces of thè cities, using their effects for a generai estimated face in thè future. The current city, thè product of these changes, will face a future in which may be affected by a complex mixture of visible and invisible factors. Influenced by several factors, cities happened to change, in historical studies. These factors could be classified into two groups:

- Controllale

- Uncontrollable factors

Each of these two main groups contains both positive and negative transforming factors inside. Each one of two transforming factor groups includes a series of events and facts that made certain changes to thè cities during history, individually or wholly, positive or negative. Through thè factors which could be considered as positive part of uncontrollable factors thè most important ones are: increase in population, economie growth, social welfare, technological development (communication technology, construetion, scientific and medicai developments, etc), relations with their vicinities, being affected by their vicinities which caused cities, countries and nations to expand, grow in dimension and make progresses, and to be recognized as industrialized, in thè way of progress, etc. Among negative category factors, lack of medicai equipments against thè epidemics, population changes caused by illnesses like pestilence, cholera, which killed so many people, mortality, naturai disasters as earthquakes, and wars which made demographic changes, could be noticed.

The effects of these factors and their results can be obviously seen either as ible facts in definite periods of time or by observing historic and statistics, following thè chronological procedure of historical events, through historical archives and documents. Logically thè percentage of contribution of positive Ifectors in bettering thè situations of cities, countries, nations during thè time , pecause of their Constant and continues impact, is more than thè negative lones and generally thè positive factors lead cities, countries and nations to become socialized, make progress and to be formed as thè civic policies. Considering these factors, current cities shape their future. Considering this assumption and through a chronological consideration of eivilizations evolutions during specific periods of time, thè future progress of tìties is partly predictable; based on these forecasts logic and oriented programs for future development of cities could be prepared through an | accurate estimation of leading factors. From one side, such predictions based on a chronological research of Ipòsitive leading factors, and from thè other side, hidden potentiality of historical cities, their cultural, historical, artistic, economical, farming, and commerciai values, which resulted diversification of thè cities and have defined main character of thè ancient cities, thè future form of cities is predictable, as we know thè current city as a complex result of its leading factors and its hidden potentiality during time. Growth in hidden potentialities of thè cities, and their logicai and historical evolution, define thè cities identity, and put them in new classification like cultural city, historical city, economical city, etc. and future politics of thè cities will be organized toward this identity. Although thè negative factors, like mentioned before, were mostly related to demographic changes, but in many cases have some drastic impacts on other aspects of thè cities life. Despite thè vast epidemics, lack of prophylactic drugs and healing medicine that caused so many changes in demographic aspect of cities, on thè other hand, thè historical wars, happened to extend thè realm and occupying new countries, caused several changes in cities both in demographical and territorial aspects. These changes happened during wars in definite periods of time, but their results, are not limited to such definite periods when they had happened and had made some unrepeatable changes, and their results are stili obvious; through thè most notable and obvious changes are thè reciprocai impacts between thè countries, which could be seen as cultural, historical, and scientific combinations between thè cities and countries during time. In this regard wars like World War I & II, their later results, in some case have had some positive effects in combination between different cultures. Scientific developments, considered as positive transforming factors, were directing different aspects of city developments since early 18th century. New inventions, new scientific theories and researches both, in new and old objects, had thè most important impact in orienting new society needs. These developments caused new changes in cities. Although development of thè cities in thè past was graduai, limited to some certain aspects and was in many cases logicai consequence of such factors, and so predictable; new city developments orientation, dependent on new factors that cause new changes based on above mentioned progresses, at an incomparable pace to past, makes cities go forward and develop so fast. Among these scientific developments, through most important ones, is development in medicai science, which, by inventing and testing new medicine, could prevent from diffusion of thè deadly epidemie illnesses, so thè direct result was saving people's life and let more people to survive. Progresses in medicai science indirectly causes increase in population, and thè naturai grow in population of thè cities, make new demands through them, perhaps thè most important, is thè need for shelter; thè new population's need for shelter leads logically cities to develop, expand both in visible forms, considering dimensions, and in hidden forms, considering relevant infrastructure systems needed to satisfy thè new cities progresses such as water consumption, gas utilization and finally electricity, and cities form changes from cities surrounded by stratification walls to expanded cities outside surrounding walls. As mentioned before, as thè new urban infrastructure demands are gas, electricity and water supplies consumption, which could be generally classified as technological improvement of thè scientific researches. These improvements, along with medicai developments, changed cities, and held a larger population. These improvements are not limited to just medicai improvements and have widespread results on other aspects of cities such as improvements in construction systems, either as improvements in traditional construction systems such as including using new materials, new methods of using them, new constructing methods, or by changing thè old System of construction, new urban typologies, and in communication systems, either accessibility by raiiroads that lead cities to be connected and shortened their distance, or by invention of telegraph and finally telephone systems which virtually connected people in different cities together. By connecting cities together, physically, thanks to railroad System, or virtually, thanks to telegraph and telephone systems, products of technological progresses, from one side and thè increase in population and thè inevitable need of shelter, from thè other side, thè old cities borders extends; cities have to give an appropriate response to new changes, new forms and new needs of ever-growing new societies, which introduces, in many cases, totally new subjects into urban life. During these changes, urban texture, formed during time and in a logically path, develops, changes, and has to match itself with new urban developments, like transportation (e.g. tramway) that made possible thè communication between different parts of thè city in a short time.