The use of mathematics in Iranian art and architecture has a long history. Geometry plays a fundamental role in traditional Iranian art and architecture. Within the structured framework of geometry, the elements of a city can connect to the universe, allowing them to achieve their identity amidst diversity and differences. This study examines the role of geometry and the numbers eight and four in Islamic art and architecture. A descriptive-analytical approach was adopted, and data were gathered through field studies, observations, and library research.This research shows that geometry in Islamic architecture is utilized not only in the appearance and structure of buildings but also as a metaphor for the spiritual world. Specifically, geometric order and symmetry are considered reflections of divine unity in the material world. The use of geometric shapes like squares, circles, octagons, and other symmetrical patterns in architectural plans and facades indicates that Islamic architects paid close attention to creating harmony and balance among the various components of buildings. By examining various examples of mosques and historical buildings, it becomes evident that these architects used geometry not only for practical purposes but also as a tool to express deep philosophical, religious, and mystical beliefs. This research emphasizes that geometry and mathematics have played a foundational role in Islamic art and architecture, enabling architects to create structures of order, beauty, and profound spirituality.