In the 18th century, the reform movements of the Ottoman Empire are generally referred to as "Westernization." During this century, the reforms and changes made in the military field were primarily oriented towards France. It is also known that the changes and innovations seen in Ottoman architecture starting from the reign of Sultan Mahmud I were influenced by the West. This study examines Westernization in Ottoman architecture through the works produced during the terms of office of the chief architects El-Hac Mustafa Ağa, Kara Ahmed Ağa, and Mehmed Tahir Ağa.

The years these architects served as chief architects at the head of the Imperial Architects' Guild during the reigns of Sultan Mahmud I, Sultan Mustafa III, and Sultan Abdülhamid I have been fully established for the first time, supported by archival documents. Their original surviving works built in Istanbul concretely demonstrate the innovations of their era. Furthermore, this study also focuses on the establishment, development, and duties of the Imperial Architects' Guild, in addition to these works.