Assassin Dens consisted of towers and their adjoining buildings, and were used by the Assassins both as headquarters and as a means of monitoring a city or district. They were ideal locations for the Templars as well, who staged many attacks to claim the dens for themselves.
Many dens were found across several Mediterranean cities during the 16th century, with eight found scattered in the districts of Constantinople. These eight towers shared the same appearance, and each held a spot for a signal fire, and an Assassin insignia at its pinnacle.
The buildings adjacent to the den towers would commonly house a main room with a fireplace, a place to smoke, and a desk from which Assassins could coordinate the movements of their brothers for defending the Mediterranean coast from Templar influence. There were also two inner balconies, one accessible via stairs and the other by a ladder. The larger of the two held a bomb-crafting station, as well as many chests.
- Main article: Den Defense
The Ottoman Assassins fought to defend their dens in Constantinople, though a Master Assassin, such as their leader Yusuf Tazim, was often needed to personally oversee and direct the defense. When Mentor Ezio Auditore da Firenze arrived in the city in 1511, he aided them by acting as commander for some of these attacks as well.
Should an Assassin complete his or her training to become a Master Assassin, they could be assigned as the master of a particular den; which they could protect without the help of other high-ranking Assassins.
The Assassins of Constantinople closely aided many other nearby cities as well, and would establish dens within them to increase their influence on the local populace.
Whenever the Assassins successfully repelled an attack, the Templars would often send further attempts to take the den, particularly should the Assassins become notorious within the city.
Similarly to Master Assassins, Templar Den Captains would be assigned to guard a den. However, often on these occasions, Ezio would use his talent to identify the Captain and eliminate him.
Upon doing so, simply lighting the signal fire atop the tower of the Assassin den would signal to the Templars that their Captain had fallen, and most soldiers would withdraw without a fight.
- Galata headquarters
- Galata Den
- North Imperial Den
- Southern Imperial Den
- North Bayezid Den
- South Beyazid Den
- North Constantine Den
- South Constantine Den
- Grand Bazaar Den
- Templar-controlled dens were a conceptual evolution of the Borgia Towers from Assassin's Creed: Brotherhood.
- Reclaiming a den would switch nearby Byzantine guards in the area with Ottoman ones, who would still react to crimes, but were not immediately hostile.
- In Mediterranean Defense, there was a limit of five apprentices per city. 65 apprentices were required to completely garrison the dens in all cities.
- When looking at a den with Eagle Vision, even when it was occupied by Byzantines, it would be marked with blue, showing it to be an allied structure.