The unique history of Istanbul left it with a unique blend of styles, culture and art, and its strategic importance throughout history left it with monumental structures built for various strategic purposes, such as guarding the city, conquering it, or keeping treasures safe. In this city’s rich and turmoiled history, various conquerors and great emperors have had Istanbul as a key point in their megalomaniac interests, especially in the medieval times. The Bosphorus had to be overseen and controlled and the passage of enemy troops and goods had to be stopped, while ensuring safe transport for the people of Istanbul and others who enjoyed its friendly embrace. Since art, wealth and goods were constantly poured into this great city from all the corners of the known world, their security had to be taken care of, as well as the security of military supplies and troops. As it can be concluded from all these reasons, the building of towers, walls, castles and fortification in general was a task of great importance which had to be conducted by only the finest architects and masons and overseen by the emperors themselves. Hence, Istanbul today has an amazing collection of fortified buildings that have stood the test of time and are accessible to all the people coming to this city for a touch of history. Below you will find listed some of them that are worth mentioning.