Kolkata, one of India’s oldest metropolitan cities, is facing a growing crisis in the loss of open spaces and the decline of its urban heritage. This study examines the impact of rapid urbanization on the city’s cultural and historical fabric, focusing on the shrinking of open spaces and the erosion of its architectural heritage. As Kolkata experiences uncontrolled urban growth, the expansion of commercial and residential spaces has resulted in the encroachment of public parks, historic sites, and green spaces, causing irreversible damage to the city’s identity. Using a combination of archival research, field surveys, and contemporary urban studies, this paper analyzes the causes and consequences of this transformation. It highlights how the loss of open spaces not only affects the city’s aesthetic and environmental value but also contributes to social inequality and public health challenges. Furthermore, the study discusses the importance of preserving urban heritage as an essential part of Kolkata's cultural identity and explores potential policy interventions for sustainable urban development. This paper calls for a more balanced approach to urban planning that recognizes the value of heritage conservation and the necessity of preserving open spaces for future generations.