Guard tower

Guard Towers are special view points in Assassin's Creed, and at least one can be found in every district. Their presence is scaled down in Assassin's Creed II, but a variant reappears in Assassin's Creed: Brotherhood.
Use
In Assassin's Creed, guard towers are used in every sequence. In order to gain full Synchronization with Altair, the player must climb each viewpoint and sychronize with it to reveal nearby portions of the map.
Guard towers are basically the center of guard activity in the district. They are guarded by several high-ranking guardsmen, with more patrolling the area. A single archer is always found on its pinnacle height.
During an assassination, if your cover is blown and your target sees you, they may turn and flee towards their district's guard tower. Upon reaching it, they become more difficult to kill, as they will be reinforced by several guards.
Trivia
- There are only four targets that flee to a guard tower: Abu'l Nuqoud, Talal, Sibrand and Jubair al Hakim.