Tyre is a city in Lebanon, famed in the Third Crusade for its unassailable defenses. Under Conrad of Montferrat, it was the only city of the Kingdom of Jersualem to have defended itself successfully against the conquest of Saladin.
During the Third Crusade, Tyre was under the control of the Crusaders and housed two of the Templars' major bases of operations: the Stronghold and the Hospital. It also had an active Assassin presence, with a carpet merchant by the name of Hamid presiding over the local Assassin bureau.
In 1190, the Assassin Altaïr Ibn-La'Ahad visited the city three times during his mission to recover the Chalice. In the first of these three visits, he infiltrated the Templar Hospital in order to kill the doctor Roland Napule and retrieve the second key to the Temple of Sand. After his failure to find the Chalice in that temple, he returned to track down the Templar leader Basilisk as his only lead to the artifact. He scaled the great wall of the heavily reinforced Templar's Hold, infiltrated the fortress, and nearly killed Basilisk in exchange for the location of the Chalice.
When Altaïr discovered that the Chalice was his friend Adha all along, the two plotted to flee the conflict between the Assassins and Templars by sailing across the Mediterranean Sea. It was from the Tyre docks that they planned to make their escape, and Adha waited there while Altaïr assassinated the Assassin traitor Harash in Alep. By the time he arrived to reunite with Adha, she had been captured by the Templars, who had their entire army occupy the harbor. In his frantic attempt to rescue Adha, he slew Basilisk in a final duel, but was unable to save his lover, who was taken by the Templars on a ship across the sea and later murdered.