This chapter investigates the historical, spatial, and environmental evolution of Bushehr, a coastal city located along the northern Persian Gulf, with over three millennia of urban continuity. It explores the development of Bushehr’s vernacular urban fabric—formed by four primary neighborhoods—through a chronological analysis of aerial images (1956–2025) and climate-responsive design logic. The chapter emphasizes how traditional morphology, shaped by socio-cultural layering and hot–-humid climatic conditions, achieved environmental adaptability through passive strategies such as compact alleyways, shaded courtyards, and wind-oriented layouts. It also documents the gradual disruption of this system due to war, modernization, and administrative interventions, which weakened spatial coherence and thermal performance. Drawing on cultural, architectural, and climatic data, the chapter frames Bushehr’s traditional settlement not only as a historical artifact but as a living source of spatial intelligence for contemporary sustainable design in coastal environments increasingly challenged by global warming.