Despite the rapid changes in cities, the transformation of the geography, terrain, and location on which they are built occurs naturally and in small amounts over an extended period. While small time units such as hours, days, and months govern living beings, geological processes have shaped the Earth’s surface for millions of years. This geological structure in the Earth’s crust also influences the architectural structures and living organisms built upon it. Lynch evaluates urban identity based on five criteria: paths, nodes, landmarks, edges, and districts. Users and environmental influences contribute to urban identity. Environmental influences encompass natural and artificial elements such as geological features, climate, location, vegetation, buildings, roads, squares, and parks. User influences denote economic, cultural, and demographic factors. This study examines the geological impact that affects urban identity, focusing on the unique stone texture derived from the geological layer constituting the city. Diyarbakir is on a vast plain, 100 m above the Dicle River, in the eastern basalt plateau, extending from Karacadag to Dicle. Due to its geological infrastructure, the region is rich in basalt stone resources, playing a significant role in the local architecture. This study aims to investigate basalt stone’s role in shaping Diyarbakir’s urban identity. Examples from monumental and civil architectural structures in Diyarbakir, located in the southeastern part of Turkey, were researched within the scope of the study. The discussion and conclusion of the study explore how the basalt stone, obtained as a geological result specific to the region, is reflected in the architecture and influences the urban identity of Diyarbakir.