Byblos was important well before the Romans, in fact it is one of the oldest continually inhabited places, settled from the 5th millenium BC. Colonized by the Pheonecians in the 3rd millenium BC, they made it a religious center with the Temple of Baalat Gebal, which was famous throughout antiquity. Close connections with Egypt, Mesopotamia, Mycenae helped to influence its culture and style, as did the invading Amorites, who built the underground royal tombs and the temple to Resheph, and the invading Hyksos from Western Asia. In subsequent periods it was ruled by the Egyptians, Greeks, Assyrians, and Neo-Babylonians, as well as Alexander the Great.
Rome, then Byzantium, then the Muslim invaders in 636, then the Crusader Raymond de Saint-Gilles, Count of Tripoli. 1266 it went back to the Muslims, and in 1516 to the Turks. It was known as Gebal in the Bible and Giblet by the crusaders, now Jbail in Arabic. Byblos, however, is said to come from the Greek word for a collection of papyrus due to it being a stop off point for ships going from Egypt to Greece, and it is to it we obtain our words books and Bible.
With a deep moat around it, the crusader castle is by far the most dominant structure in the ruins, and was made with Roman stones from the area. Built by the Franks in the 12th Century, it is 49.5m by 44m and has a huge cystern making up the bottom basement level.