The mosques of Rüstem Pasha, one of the most successful businessmen of the Ottoman Classical Period, located in Istanbul-Eminönü and Tekirdağ-Rodosçuk, show similar features in many ways but also differ in some respects. In this study, the formation features of these mosques both of which were designed by Architect Sinan, are examined, and the factors causing similarities and differences are analized according to the position of the mosques in the plan type evolution of Architect Sinan’s mosques and also according to the location, planning, material and facade characteristics of the buildings. This study concludes that, despite the architect of both mosques being the same person, some challenging factors played an important role in the design of the mosques, both of which are located at strategic sea and land trading point . The afore-mentioned challenging factors are the location of the buildings and their architecture in the light of this location, the fact that they were built before or after the death of the ban, and local influences on the use of ornamental elements and building materials. Both of the mosques are domed, double-porticoed and single-minaret and were built at about a 10 year interval. While the mosque in Istanbul is the largest vizier mosque of payitaht with a dense usage of tiles and other ornamental elements used in its architecture, the mosque in Tekirdağ displays a more provincial character, as seen in its architectural features.