The earliest settlement of Beirut was on an island in the Beirut River, but the channel that separated it from the banks silted up and the island ceased to be. Excavations in the downtown area have unearthed layers of Phoenician, Hellenistic, Roman, Byzantine, Arab, Crusader, and Ottoman remains. Prehistory

Beirut was settled over 5,000 years ago,Under Beirut's Rubble, Remnants of 5,000 Years of Civilization– NYTimes 23 February 1997 and there is evidence that the surrounding area had already been inhabited for tens of thousands of years prior to this. Several prehistoric archaeological sites have been discovered within the urban area of Beirut, revealing flint tools from sequential periods dating from the Middle Palaeolithic and Upper Paleolithic through the Neolithic to the Bronze Age.

BeirutI (Minet el-Hosn) was listed as "the town of Beirut" () by Louis Burkhalter and said to be on the beach near the Orient and Bassoul hotels on the Avenue des Français in central Beirut.Burkhalter, L., Bibliographie préhistorique (à suivre) (List of prehistoric sites, continuation and end), Bulletin du Musée de Beyrouth. Tome VIII, 1946–1948, Beyrouth, in-4° br., 173 pages.Burkhalter L., Bibliographie préhistorique (suite et fin) (List of prehistoric sites, continuation and end), Bulletin du Musée de Beyrouth. Tome IX, 1949–1950, Beyrouth, in-4° br., 117 pages. The site was discovered by Lortet in 1894 and discussed by Godefroy Zumoffen in 1900. The flint industry from the site was described as Mousterian and is held by the Museum of Fine Arts of Lyon.

BeirutII (Umm el-Khatib) was suggested by Burkhalter to have been south of Tarik el Jedideh, where P.E. Gigues discovered a Copper Age flint industry at around above sea level. The site had been built on and destroyed by 1948.

BeirutIII (Furn esh-Shebbak), listed as , was suggested to have been located on the left bank of the Beirut River. Burkhalter suggested that it was west of the Damascus road, although this determination has been criticized by Lorraine Copeland. P. E. Gigues discovered a series of Neolithic flint tools on the surface along with the remains of a structure suggested to be a hut circle. Auguste Bergy discussed polished axes that were also found at this site, which has now completely disappeared as a result of construction and urbanization of the area.Bergy, Auguste. "La paléolithique ancien stratifié à Ras Beyrouth". Mélanges de l'Université Saint Joseph, Volume 16, 5–6, 1932.

BeirutIV (Furn esh-Shebbak, river banks) was also on the left bank of the river and on either side of the road leading eastwards from the Furn esh Shebbak police station towards the river that marked the city limits. The area was covered in red sand that represented Quaternary river terraces. The site was found by Jesuit Father Dillenseger and published by fellow Jesuits Godefroy Zumoffen, Raoul DescribesDescribes, Raoul. "Quelques ateliers paléolithiques des environs de Beyrouth", Mélanges de l'Université Saint-Joseph, Volume VII, 1921. and Auguste Bergy. Collections from the site were made by Bergy, Describes and another Jesuit, Paul Bovier-Lapierre. Many Middle Paleolithic flint tools were found on the surface and in side gullies that drain into the river. They included around 50 varied bifaces accredited to the Acheulean period, some with a lustrous sheen, now held at the Museum of Lebanese Prehistory. Henri Fleisch also found an Emireh point amongst material from the site, which has now disappeared beneath buildings.

BeirutV (Nahr Beirut, Beirut River) was discovered by Dillenseger and said to be in an orchard of mulberry trees on the left bank of the river, near the river mouth, and to be close to the railway station and bridge to Tripoli. Levallois flints and bones and similar surface material were found amongst brecciated deposits.Karge, P., Rephaim : Die Vorgeschichtliche Kultur Palästinas und Phöniziens, Paderborn (First edition), 1917–1918 The area has now been built on.Zumoffen, Godefroy., L'âge de la Pierre en Phénicie, L'Anthropologie, Volume 8, page 272, 1898.

BeirutVI (Patriarchate) was a site discovered while building on the property of the Lebanese Evangelical School for Girls in the Patriarchate area of Beirut. It was notable for the discovery of a finely styled Canaanean blade javelin suggested to date to the early or middle Neolithic periods of Byblos and which is held in the school library.

BeirutVII, the Rivoli Cinema and Byblos Cinema sites near the Bourj in the Rue el Arz area, are two sites discovered by Lorraine Copeland, Peter Wescombe, and Marina Hayek in 1964 and examined by Diana Kirkbride and Roger Saidah. One site was behind the parking lot of the Byblos Cinema and showed collapsed walls, pits, floors, charcoal, pottery and flints. The other, overlooking a cliff west of the Rivoli Cinema, was composed of three layers resting on limestone bedrock. Fragments of blades and broad flakes were recovered from the first layer of black soil, above which some Bronze Age pottery was recovered in a layer of grey soil. Pieces of Roman pottery and mosaics were found in the upper layer. Middle Bronze Age tombs were found in this area, and the ancient tell of Beirut is thought to be in the Bourj area.Lauffray, J., Forums et monuments de Béryte, Bulletin du Musée de Beyrouth. Tome VII, 1944–1945, Beyrouth, in-4° br., 124 pages dont 4 de texte arabe, 29 planches hors-texte.

Phoenician period

The Phoenician port of Beirut was located between Rue Foch and Rue Allenby on the north coast. The port or harbour was excavated and reported on several years ago and now lies buried under the city. Another suggested port or dry dock was claimed to have been discovered around to the west in 2011 by a team of Lebanese archaeologists from the Directorate General of Antiquities of Lebanese University. Controversy arose on 26 June 2012 when authorization was given by Lebanese Minister of Culture Gaby Layoun for a private company called Venus Towers Real Estate Development Company to destroy the ruins (archaeological site BEY194) in the $500 million construction project of three skyscrapers and a garden behind Hotel Monroe in downtown Beirut. Two later reports by an international committee of archaeologists appointed by Layoun, including Hanz Curver, and an expert report by Ralph Pederson, a member of the institute of Nautical Archaeology and now teaching in Marburg, Germany, dismissed the claims that the trenches were a port, on various criteria. The exact function of site BEY194 may never be known, and the issue raised heated emotions and led to increased coverage on the subject of Lebanese heritage in the press.Ralph K. Pederson, Archaeological Assessment Report on the Venus Towers Site (BEY 194), Beirut – For the Venus Towers Real Estate Development Company, Philipps-Universität Marburg, 30 May – 3 June 2012.

Hellenistic period In 140BC, the Phoenician city was destroyed by Diodotus Tryphon during his conflict with Antiochus VII Sidetes for the throne of the Hellenistic Seleucid monarchy. Laodicea in Phoenicia was built upon the same site on a more conventional Hellenistic plan. Present-day Beirut overlies this ancient one, and little archaeology was carried out until after the civil war in 1991. The salvage excavations after 1993 have yielded new insights into the layout and history of this period of Beirut's history. Public architecture included several areas and buildings.

Mid-1st-century coins from Berytus bear the head of Tyche, goddess of fortune; on the reverse, the city's symbol appears: a dolphin entwines an anchor. This symbol was later taken up by the early printer Aldus Manutius in 15th century Venice. After a state of civil war and decline the Seleucid Empire faced, King Tigranes the Great of the Kingdom of Armenia conquered Beirut and placed it under effective Armenian control. However, after the Battle of Tigranocerta, Armenia forever lost their holdings in Syria and Beirut was conquered by Roman general Pompey.

Roman period

Laodicea was conquered by Pompey in 64 BC and the name Berytus was restored to it. The city was assimilated into the Roman Empire, soldiers were sent there, and large building projects were undertaken.About Beirut and Downtown Beirut , DownTownBeirut.com. Retrieved 17 November 2007. From the 1st century BC, the Bekaa Valley served as a source of grain for the Roman provinces of the Levant and even for Rome itself. Under Claudius, Berytus expanded to reach the Bekaa Valley and include Heliopolis (Baalbek). The city was settled by Roman colonists who promoted agriculture in the region.

As a result of this settlement, the city quickly became Romanized, and the city became the only mainly Latin-speaking area in the Syria-Phoenicia province.Morgan, James F. The Prodigal Empire: The Fall of the Western Roman Empire, page 87 In 14BC, during the reign of Herod the Great, Berytus became a colony, one of four in the Syria-Phoenicia region and the only one with full Italian rights () exempting its citizens from imperial taxation. Beirut was considered the most Roman city in the eastern provinces of the Roman Empire. Furthermore, the veterans of two Roman legions were established in the city of Berytus by emperor Augustus: the 5th Macedonian and the 3rd Gallic Legions.

The Lebanese Roman Latin grammarian, literature master, philologist and critic Marcus Valerius Probus, who flourished under the reign of Nero, was born in Berytus, ., in the same century, the Judean ruler Agrippa II expended large sums in beautifying Berytus, a Hellenised city in Phoenicia. His partiality for the Lebanese city rendered him unpopular amongst his Jewish subjects. There was a Christian presence in Berytus since the first century, with the discipline Quartus being the bishop of Berytus , and according to tradition, Thaddeus, together with Simon the Zealot, both apostles of Jesus, suffered martyrdom about AD 65 in Beirut.Golden Legend

Shortly after the acclamation of Vespasian as Roman emperor had occurred at Alexandria on July 1, Vespasian and Mucianus – a prominent senator, governor of Syria, and a man who had been instrumental in persuading Vespasian to bid for the imperial throne – held a conference at Berytus, planning their campaign in mid-July, AD 69. There is evidence in the 1st century works of Josephus of substantial Jewish interest in silk, both in trade and production, especially in Berytus and Tyre. In the Roman period, Jiyeh was a production site of Beirut Type 2 amphorae transporting olive oil from the 1st century AD onwards.American University of Beirut Roman amphorae in the Near East: a study of the distribution of Spanish, North African, and local types by Naseem Naji Raad

During the 2nd century, the 115 Antioch earthquake in which Beirut suffers significant damage, occurred on 13 December 115 AD. In the same century, after the death of the Roman emperor Commodus, a civil war erupted, in which Berytus, and Sidon supported Pescennius Niger. While the city of Tyre supported Septimius Severus.Herodian, Roman History 3.3.

Berytus's law school was widely known;, Britannica.com in 238 or 239 AD, the city was first mentioned in writing as a major center for the study of law in the panegyric of Gregory Thaumaturgus, the bishop of Neo-Caesarea, p. 289, p. 17, pp. 45–46 The 3rd-century emperors Diocletian and Maximian issued constitutions exempting the students of the law school of Beirut from compulsory service in their hometowns., p. 65Collinet 1925, pp. 29–30 and two of Rome's most famous jurists, Papinian and Ulpian, were natives of Phoenicia and taught there under the Severan emperors. When Justinian assembled his Pandects in the 6th century, a large part of the corpus of laws was derived from these two jurists, and in AD533 Justinian recognised the school as one of the three official law schools of the empire.