New structures in historical textures (Yazd)

New constructions in the historical textures is an unavoidable necessity in terms of maintenance and continuity of the physical, social and economic life of the texture and also in order to improve the conditions of life and the level of welfare and to be coordinated with the needs and requirements of the day. But this necessity causes some damage to the overall image and appearance of the historical cities if it doesn't have a proper and wise approach. So, first of all, in the formation of new construction in the historical texture, a designer shall remember what will be constructed, it will have a role in the historical texture as a part of city prior to being just an architectural building. Since a cohesive and durable rule shall exist between the historical sections and new constructions in order for them to be together and coordinate, in this article, it is attempted to review the ways to maintain unity and coherence of the appearance of the historical and new texture in Yazd and we have and to refer to some efficient solutions and principles in this respect. The present research has been done with a descriptive - analectic method and based on the library studies.