Towering above Tripoli and the river, this Crusader fortress was originally built during the period from 1103 to 1104. Burned down in 1297, it was partly rebuilt the following century by a Mamluk emir and is still used by the Lebanese military. Today, it's an impressive structure whose most impressive element is the imposing entrance with its moat and three gateways (one Ottoman, one Mamluk, one Crusader). Inside, there are decent information panels as well as a small museum.
The existence of this castle eventually led to the city of Tripoli being centred here, rather than down by the water at Al Mina. Look out for the mashhad (octagonal mausoleum) that was the centre of a Fatimid cemetery. The views from the ramparts are excellent.
At time of research the castle was being partly used as a barracks so entrance was free, but admission fees may return.