In the fifteenth century, the Mediterranean world was in turmoil. A new sultan, Mehmet II, had just inherited a vast empire stretching over two continents in the centre of which the ruins of the Byzantine Empire survived through the city of Constantinople. In order to seal his accession, he therefore undertook important preparations to conquer the “City guarded by God”. Mehmet then ordered the construction, within 4 months, of an imposing fortress nicknamed Boǧazkesen (the throat cutter). This coup de force is a testimony to the incredible military and economic power of this growing empire that masters a new war technology: artillery. The Ottomans, who were still novices in this field, had therefore had to adapt their fortifications to the use of firearms. Using local and foreign architects and engineers, the Ottoman fortifications built in the fifteenth and sixteenth centuries bear witness to an architectural experimentation that seems to testify, like the work carried out in Rhodes by Pierre d’Aubusson or in Methoni by the Venetians, to a real research in terms of offensive and defensive effectiveness. In this context, the fortifications of Rumeli Hisarı and Anadolu Hisarı, built on either side of the narrowest point of the Bosporus in 1451-1452, are characterized by the presence of large coastal batteries that operate together. They were to block access to Constantinople by the Black Sea, combining sinking and dismasting fire.