Historical structures hold both tangible and intangible values which contribute to the identity of the place. The built heritage of historic towns holds architectural, archaeological, economic, spiritual, social, and political values. These historical buildings have a strong emotional impact since they represent the culture's continuity and identity, and over time these become a part of our legacy and are called heritage structures. A heritage structure conveys timeline of messages from the very beginning of its inception till the present. Historic structures provide a physical link to the past and aid in defining the character of our communities which led to the execution of a particular building, and its further assessment provides insights to understand its overall historic value. The paper demonstrates adaptive reuse as one of the ways of conservation of built heritage. The case examples of ancient buildings from the historic cities: Diu and Ahmedabad have been discussed to understand the correlation between sustainability and adaptive reuse of historic structures. The recommendations made for the preservation of structure, suitable repair, and upkeep of historic/heritage buildings will significantly help to safeguard and improve the environment. Sustainable practices based on an integrated approach can help to preserve the overall environment of the place. The basic principles required to adopt sustainable development goals have been demonstrated through case examples.