Modern archaeological excavations have revealed that Byblos was occupied at least by the Neolithic Period (New Stone Age; c. 8000–c. 4000 BC) and that during the 4th millennium BC an extensive settlement developed there. Because Byblos was the chief harbour for the export of cedar and other valuable wood to Egypt, it soon became a great trading centre; it was called Kubna in ancient Egyptian (Egypt, ancient) and Gubla in Akkadian, the language of Assyria. Egyptian monuments and inscriptions found on the site attest to close relations with the Nile River valley throughout the second half of the 2nd millennium. During Egypt's 12th dynasty (1938–1756 BC), Byblos again became an Egyptian dependency, and the chief goddess of the city, Baalat (“The Mistress”), with her well-known temple at Byblos, was worshiped in Egypt. After the collapse of the Egyptian New Kingdom in the 11th century BC, Byblos became the foremost city of Phoenicia.

The Phoenician alphabet was developed at Byblos, and the site has yielded almost all of the known early Phoenician inscriptions, most of them dating from the 10th century BC. By that time, however, the Sidonian kingdom, with its capital at Tyre, had become dominant in Phoenicia, and Byblos, though it flourished into Roman times, never recovered its former supremacy. The Crusaders captured the town in 1103 and called it Gibelet. They built a castle there (using stone from earlier structures) but were driven out by the Ayyūbid sultan Saladin in 1189. The town subsequently sank into obscurity.

The ancient ruins of Byblos were rediscovered by the French historian Ernest Renan (Renan, Ernest), who led a survey of the area. Systematic excavations were begun there by Pierre Montet (Montet, Pierre) in 1921; in the mid-1920s Maurice Dunand resumed the work and continued it until the mid-1970s. The ruins today consist of the Crusader fortifications and gate; a Roman colonnade and small theatre; Phoenician ramparts, three major temples, and a necropolis; and remains of Neolithic dwellings. Byblos was designated a UNESCO World Heritage site in 1984.

Present-day Jbail is adjacent to the archaeological site, extending from there to the waterfront area. Tourism is a major component of the local economy. In addition to the ruins, other notable attractions are the Church of St. John the Baptist, portions of which date to the early Crusader period, and a wax museum (opened 1970) dedicated to the area's history and rural Lebanese life. Pop. (2002 est.) 18,800.