Anadolu and Rumelihisarı were built on the two shores of the narrowest point of the Bosphorus waterway, one of the strongest waterways in the world. As of 1390 AD, the Anatolian shores of Istanbul were completely under the control of the Turkish forces, and the first rehearsals of the conquest began over the Anadoluhisarı, which was built afterwards. When the calendars show the year 1452, Rumelihisarı, which was built in a short period of four months on an area of 30,000 m2, is now a harbinger of conquest. The two fortresses, located opposite each other on the Bosphorus, are the oldest structures of Ottoman Istanbul and have been the starting points of the development of the Turkish-Islamic Civilization in Istanbul, with their first Turkish quarters and their social and economic structuring as well as military success. Anadoluhisarı and Rumelihisarı are the oldest settlements in Ottoman Istanbul. Rumelihisarı was built in order to keep the passage of ships passing through the Bosphorus under control. And the superiority of its geographical position is indisputable. It controlled the Rumelian coast at the narrowest point of the Bosphorus waterway. In addition to being the narrowest part of the Bosphorus waterway, it was also the place where the current known as the devil’s current among the Bosphorus currents drifted towards the shore. Every ship going from the Black Sea to the Bosphorus had to be caught in this devil’s current and come to the position where Rumelihisarı is located and continue on its path parallel to the shore. The construction of the fort started on April 15, 1452 and was completed on August 31, 1452. Covering an area of 30 thousand square meters, the citadel, which was completed in a short time like 139 days, as a military structure in the conditions of the century, the materials in its construction, the logistics organization and construction technique in the direction of manpower are astonishing. Only 300 masters, 700-800 workers, 200 coachmen, boatmen, transporters and crew took part in the construction of Rumelihisarı. When these numbers are examined, besides the effort to finish the construction as soon as possible, there is also a discipline brought about by constructing a military strategic area in enemy territory. It is an incredible example of how well organized logistics successfully built a castle with the world’s largest bastions with 300 craftsmen, 700-800 workers, 200 coachmen, boatmen, transporters. On the other hand, most of the stone material in the construction of approximately 57,700 m3 masonry was supplied from the quarries of Istinye and transported by sea. Again, stones obtained from Kayalar Mevkii, the region where the Hisar was built, and smooth cut stones brought from Karadeniz Kefken by sea will also form the basic materials of this construction. The spolia material found on the walls and floors of Hisar today is the material obtained from the ancient Roman ruins found here. While the timber used in the construction of the fortress was procured from Iznik and Karadeniz Ereğli, the lime obtained from the lime wells that were previously created on the Anatolian side was brought here from twelve quarries opened around Çubuklu and quenched. Iron ores sent from Kavak and Büyükada were transported here. In addition to the difficulties of transporting all these construction materials and manpower transportation completely by sea; Considering the seasonal conditions of the period in which the construction started, the result of the logistics success is astonishing. Under the management of Baltaoğlu Süleyman Bey, the first Captain of the Command of the period, this shipment of the navy from Gallipoli was carried out smoothly and successfully. Rumelihisarı, which is the symbol of conquest of Istanbul today, is the first Islamic structure built by Fatih Sultan Mehmed Han in the ancient city of Istanbul. The citadel, which was built in a short time like 4 months, with its mosque, waterway, bath, its quarter and its tower with divanhane, has the world’s largest bastions with its three big towers. The construction of the Hisar was started under the administration of Fatih Sultan Mehmed Han, and its construction was also carried out by the Architect Musliheddin. The construction of each part of the fort was placed under the control of a pasha. Saruca Pasha was assigned to supervise the construction of the tower on the right, called Fatih Tower when viewed from the sea, Zağanos Pasha to oversee the construction of the tower on the Bebek side, and Grand Vizier Halil Pasha to supervise the construction of the tower on the shore. For this reason, the towers here carry the names of these pashas today. The construction of the section falling to the sea side, including the front wall surrounding the bastion on the coast, called Hisarpeçe, was carried out by Fatih Sultan Mehmed himself.