This castle might be the most important preserved medieval military landmarks in the world.
It is a crusader fortress located east of Tripoli, Lebanon, in Syria. It sits atop a 650-metre-high hill along the only route from Antioch to Beirut and the Mediterranean Sea.
It is one of many fortresses that were built as a defensive network on the boarder of the old Crusader states. This base controlled the road to the Mediterranean Sea.
During The Crusades this was an incredibly important structure. Around 1200 it was expanded to the largest crusader fortress in the Holy Land and was transformed into a concentric castle, which is a castle within another castle.
Some of the walls are over a hundred feet thick.