The article is devoted to the poorly studied history of fortification construction in the Ottoman fortress Azov (Azak), located at the Don Riverdelta. Based on a wide range of Russian and Ottoman sources (documentary, narrative and pictorial), the stages of the creation of the complex of fortifications of Azov, the evolution of its planning structure and the changes that took place in local toponymy in connection with these processes are traced. An attempt was made to determine the location and parameters of the city's fortifications in the 16th – 17th Centuries (up to 1696 inclusive). It is shown that the system of stone fortifications of Azov began to form from the time of its capture by the Ottomans in 1475, and it was based on two stone castles built by the Venetians and Genoese as early as the 14th Century. By the early 1540s, Azov had a four-part structure and included two Venetian (external and internal) and Genoese forts, as well as the Soil fort (suburb). In the mid-1570s, the Soil fort was surrounded by stonewalls and, probably, united with the rest of Azov. By the time of the capture by the Don Cossacks in 1637, Azov already had a three-part structure and consisted of adjacent Stone, Middle and Soil forts. The consequence of the Ottoman siege of Azov in 1641 was the almost total destruction of the fortifications, which then had to be rebuilt. Sources do not confirm the point of view widespread in historiography, according to which, when the Ottomans restored fortress in 1642, its layout remained unchanged. Purposeful improvement of the fortifications of Azov continued in the second half of the 17th Century, right up to the loss him by the Ottoman Empire in 1696. The Sublime Portepaid great attention to the defense capability of the northernmost outpost of the empire, responding to the growing external threat. However, the strengthening in the region of the positions of the first Don Cossacks, and then of the Russian State, made these defensive measures useless.