The participation of the public in the decision, use and maintenance of the heritage structures in the cities brings positive results to that city. Istanbul Kadikoy-Hasanpasa Gasworks was closed in 1993 and lost its function, and in 2021, it was reopened for use as a culture and art center. In the transformation decisions of the gasworks, the Gasworks Environmental Volunteers, consisting of the people of the environment, have played an active role for 27 years and continue to play a role after the transformation. This study examines the impact and efforts of Gasworks Environmental Volunteers before and after the transformation and describes a collective struggle in the participatory management of heritage. As a result of face-to-face interviews, observations, and literature research conducted with a qualitative research method, the effects of non-governmental organizations on heritage sites were examined. The data obtained will increase the awareness of the society on the heritage areas and contribute to the fact that the society will be a factor in the transformation decisions by protecting the heritage.