Historic preservation consciousness in 19th century starts with legal measures to prevent the removal of architectural fragments and movable objects from the excavations supervised by western archeologists. Besides major monuments of Seljukid, Roman, Byzantine and Ottoman periods, the reformation and westernization of the 19th century political attempts and the western urban planners taking chair in the municipality ended with planning proposals based on grid - system and cleaning of the urban texture surrounding monuments.The genius loci of the early republican era is based on creating a new westernized nation and society, positivism which contradicts with the traditional Ottoman Culture and the society. Simultaneously modernization and conservation were tried to be carried on which seemed to be contradictory those years but in fact is not.Preferring the modern international architectural style state buildings, construction of the new capital Ankara versus Istanbul and concerning traditional buildings and neighbourhoods as symbols of anti-revolution summarizes the origin of the mentality of urban renewal and the destructions. The erosion of the traditional culture gradually led to the destruction of the traditional urban texture where even mosques, madrasas and major buildings were pulled down to ground. During the Second World War “modern” meaned colossal state buildings of the national socialist ideology and the revival of the traditional Turkish house in new designs.After 1950’s the political upheaval and the stabilization under American influence after the Second World War resulted in democracy and the shift in cultural and architectural influence. However the urban renewal and the destructions continued as usual. After 1960’s the Venice Charter was accepted and discussed between scholars but a decade was necessary to be functioned in architectural conservation principles. The conservation theories at the academic levels, the legislation and the grading of the listed buildings and the levels of intervention to historic buildings were different. Still the modern - traditional conflict dissected the social memory and advocated to live in modern apartment floors as a symbol of being modern and westernized persons. Also tourism was accepted as a promoting factor in conservation which resulted in inappropriate intervention and devaluating of monuments.The dipolar and contradicting behavior of the dissected traditional memory rejected the intangible culture to be conserved together with the physical environment. This political, social and economic media was provoked by value making process in urban planning.The history of the loss of the historic buildings and the traditional urban texture was outlined to point out the irreversible change in Istanbul and the appropriateness of the reconstructions of the lost buildings in the metropolis of the 21th century Istanbul