Viewpoint

View Points were structures high enough for an observer positioned on its tallest point to view the surrounding terrain. They ranged from church towers and roof beams on a city's landmarks, to watchtowers and guard posts.

View Points were essential for allowing an individual to collect their bearings, and navigate a landscape.

High Middle Ages
View Points could be found in the cities of Damascus, Jerusalem, and Acre, as well as the Kingdom, but not in Masyaf.

Each city contained ten to twelve View Points located on the highest buildings; such as a cross on top of a Catholic cathedral, the top of a lighthouse in the port-city of Acre, or a palace guard tower in the city of Damascus. Individuals adept in freerunning, such as Assassins, would climb View Points to survey the area and take note of the people within the city, and their movements.

Some View Points, such as watchtowers, had archers defending the position, or guards set around and below it, who could either fire arrows or throw rocks to prevent anyone climbing from reaching the top. At the very bottom of the View Point, carts or piles of hay were conveniently positioned, providing safe locations for the performance of a Leap of Faith.

Renaissance
During the Renaissance, View Points functioned much as they did during the Third Crusade, and some were located on famous landmarks of the era. Assassins made extensive use of these, and would not only be able to dive into carts and stacks of hay, but also into those of flower petals, leaves, and spices, as well as into bodies of water.

In the cities of Rome and Constantinople, various towers, such as Borgia Towers and Assassin Dens, possessed a commanding view over the surrounding area, and could be used for the same purpose as a View Point.

Many View Points were located on famous monuments, such as the Pantheon, Colosseum, Hagia Sophia, and Topkapı Palace.

American Revolutionary War
Shortly before, and during the American Revolutionary War, View Points retained their function of providing an ancestor with bearings of the surrounding area, and were once again located on famous landmarks of the era, as well as high points in the Frontier such as trees on the hilltops.

Contrary to the View Points used by other ancestors, the ones in America revealed only small bits of landscape, leaving the area open to exploration even after all of the View Points were synchronized.

Haytham Kenway and Ratonhnhaké:ton utilized View Points in Boston, New York and Frontier, and could perform a Leap of Faith to descend from them. In addition to previously seen places such as haystacks or water, they could also perform the maneuver into a moving cart, if it happened to be passing underneath the View Point.

Animus
When Desmond Miles relived the memories of his ancestors through the Animus, View Points served an additional function. They would unlock parts of the Animus map, and displayed the location of various events that occurred throughout his ancestors' lives.

When he relived Altaïr Ibn-La'Ahad's memories, he was required to climb a View Point whenever he entered a new city. On synchronizing with this View Point, the Animus map would display all the other View Points, along with the location of the Assassins' Bureau in the city.

Climbing the View Points also allowed Desmond to find sources of information that he could investigate, and use to gain information on Altaïr's targets.

View Points served a similar function in the Animus 2.0, through which Desmond relived Ezio Auditore da Firenze's memories. It also helped Desmond locate side memories, such as races, message deliveries, assassination contracts, and beat-up events.

Trivia

 * In Assassin's Creed, the "Fearless" achievement could be obtained by synchronizing with all viewpoints.
 * In Assassin's Creed, View Points were referred to as either "Reach High Points" or "Eagle Points".
 * In Assassin's Creed II, the "I Like the View" achievement could be obtained by synchronizing with ten View Points.
 * In Assassin's Creed II, the "High Dive" achievement could be obtained when Ezio performed a Leap of Faith from the top of the Campanile di Giotto View Point in Florence.
 * In Assassin's Creed, Altaïr could activate Eagle Vision once he had synchronized with the View Point. However, in Assassin's Creed II and Assassin's Creed: Brotherhood, attempting to do so would simply have Ezio observe his surroundings again.
 * In each game, the highest point was either inaccessible or not a View Point. In Assassin's Creed, it was located in the fortress of Masyaf; in Assassin's Creed II, it was the Basilica di Santa Maria del Fiore; in Assassin's Creed: Brotherhood, it was the Castel Sant'Angelo, and in Assassin's Creed: Revelations, it was the pinnacle of the Galata Tower, or one of the Hagia Sophia's minarets.
 * Throughout the Assassin's Creed series, an Assassin could be on the View Point at the same time the eagle was, causing the eagle to clip through them.
 * In Assassin's Creed: Bloodlines, View Points were referred to as "High Points".