Bureaus acted as sanctuaries for members of the Assassin Order, where their users could physically and mentally prepare themselves for a mission, allowing them to restock on weapons, sleep or meditate. It also allowed Assassins a place to wait for the appropriate moment to strike, or for the dust to settle after an assassination.
Inside each bureau resided a leader, who held either the rank of Rafiq or higher. They would often give Assassins useful information on where to learn more about assassination targets. Once the strike had been planned and approved by the bureau leader, an Assassin was given a feather to soak in the blood of their target as proof of their success.
The exterior of the building was typically quite discreet, resembling that of common construction, although they did not have any obvious windows or doors.
The entrance was usually located on the roof, which could be reached by either climbing the walls or via a ladder located in an entry alley, for instance. This was likely to be a measure to prevent curious civilians (or more importantly, the city guards), from stumbling upon it.
The main chamber served as the entrance hall to the bureau, and was a small living area comprised of two fountains, potted plants and several pillows and carpets. This place was intended as a location for Assassins to rest before and after assassinations.
The walls were decorated with hanging carpets and the Assassin insignia, while the ceiling was grated with an opening that acted as an entrance into the Bureau. When the city guards were on alert, the opening was closed with a grated panel.
A bureau leader's chamber was adjacent to the main chamber. From behind a desk, each leader addressed those who would come to speak with them, while also studying and attending to the Assassin Order's operations in that respective city.
Behind the desk were bookshelves and closets, where registries of missions were kept. The books and scrolls the leader had access to were also located in this area.
Across the room, a raised walkway held weapons, books, and other items that could assist Assassins in their missions.
18th century Caribbean
During the early 18th century, the bureaus spread throughout the major cities in the West Indies varied in size and description; the bureaus in Havana and Kingston held at least one building and had a surrounding courtyard or walls, the Nassau bureau consisted of a small collection of buildings, and the Cayman 'ghost' bureau had no defined buildings or areas to speak of.
After killing the traitorous Duncan Walpole in 1715, Edward Kenway recovered and subsequently sold a map detailing the four bureaus' locations to the Templars operating in the region, unwittingly putting the Assassins stationed there in danger. Edward eventually traveled to the four bureaus and made amends for disclosing their locations; in doing so, he assisted the bureau Masters in various ways, in return for a collection of keys that would grant him access to a set of Templar Armor.
- Altaïr Ibn-La'Ahad could return to a bureau any time to restock on throwing knives.
- A bureau's entrance would be closed when social status was exposed to prevent guards from discovering the Bureau and subsequently violating a tenet of the Creed.
- During the Third Crusade, the Acre bureau was lined with books, while the Damascus bureau was lined with pottery.
- Accompanying this, there was also a chess board inside the Assassin bureau of Damascus.