The Citadel of Tripoli is a massive structure on a hilltop overlooking Nahr Abou Ali river, built by the Arabs in 636 and subsequently enlarged and modified by the Fatamids of Egypt, the Crusaders and the Ottomans.
The Citadel of Tripoli also known as Qalaat Tarablous or Kalaa, or Crusader Castle of Saint-Gilles, is one of the largest and oldest military fortresses in Lebanon. It was initially constructed by the Arab commander Sufyan Ben Mujib Al-Azdi in 636 CE. The Fatimids later added a mosque to it during the 11th century CE. Raymond de Saint-Gilles, the Count of Toulouse and Crusader commander enlarged it again in 1103 to become the fortress Mont Peregrinus (Mt Pilgrim) in order to lay siege to the city.
The Mamluk Prince Asandamor al-Kurji enlarged the fortress yet again in 1307 CE and turned it to a citadel by building some towers inside. The Ottoman Sultan Selim Ben Selim el-Awal commissioned the construction of the northern tower that includes the main gate of the citadel.
The beautiful oriental white structure below it is an old school called Madrassat Al Houda.