Tehran has a vast treasure of tangible and intangible historical heritage, which is deteriorating and being forgotten due to the need for integrated and coherent measures. So far, there have been many interventions in the historical context of this city, which, due to the lack of attention to the background and context, and only by carrying out physical measures, not only did not help to improve the conditions but also added to the problems of the historical context and, as a result, made the historical context more exposed to destruction. In this article, an attempt has been made to examine the legal bases and principles compiled in the laws and regulations regarding restoration and new designs in the historical context of Tehran, as well as how these actions are carried out in this context. The research method is analytical-descriptive and based on library studies and a review of available sources. First, the definition of historical context and cultural heritage is discussed. The decision-making authorities of these contexts are introduced. Then, the restoration, restoration principles, and construction and design principles in the historical context are explained. This research also leads to the basics and rules about the design and construction of new architecture in the vicinity or within historical contexts. It includes the methods of restoration and conservation interventions.