Answer: Constantinople
Step-by-step explanation:
Byzantium has, for centuries, been a barrier to the overflow of Islam into Europe. Eventually, in 1453 it fell into the hands of the Ottomans. Islam spread from the east, and Constantinople was a barrier to further expansion. When Mehmed II conquered Constantinople, the city became the Ottoman capital, and it was from that administrative and political center that the Ottomans organized further military campaigns towards Europe. In this way, they also tried to spread Islam. There are several examples where they have succeeded in these endeavors. These examples are obvious in some countries of Southeast Europe.