Mimar Sinan served as the chief architect from 1538-1588 in the GoldenAge of the Ottoman Empire. He was responsible for the design andconstruction of over 470 buildings of different sizes and functions.Unfortunately, Sinan’s methods of shaping, sizing, and construction areunknown since no records of his design principles have been found;however, the simultaneous construction of many buildings throughoutthe empire suggests that he used a common method, especially in thedesign of simple buildings of similar size and shape. In this study, TheFerhat Pasha Complex in Çatalca, İstanbul has been chosen as anexample to investigate Sinan's design principles. In the first phase of thestudy, the compatibility of the examined building’s plan with themethods known to be used in different civilizations, like quadrature,golden ratio, grid system, etc., were investigated, revealing that the sizes,forms, and locations of buildings in the complex are in accordance witha modular grid system which was created with zira, an Ottoman unit ofmeasurement. In the study’s second phase, the stages in the emergenceof building design were shown by the inductive method. This system alsoplayed an important role in estimating the cost of the buildings and,tracing the outlines of the plans to the ground in cases where thedesigner cannot be found personally.