Short answers, pulled from the story.
The Phoenician village called Biruta lay in ruins after Diodotus Tryphon destroyed it during a struggle for the Macedonian Seleucid throne in 140 BC. The Seleucids reconstructed the site as Laodicea in Phoenicia by 110, 109 BC to honor a royal woman named Laodice.
Augustus established veterans from two Roman legions in the city: the fifth Macedonian and the third Gallic. By 14 BC, Herod the Great oversaw the transformation into Colonia Iulia Augusta Felix Berytus with two-thirds of the inhabitants being descendants of these soldiers.
A series of earthquakes in the sixth century demolished most temples of Heliopolis and leveled the city of Berytus. An anonymous pilgrim of Piacenza recorded that nearly 30,000 inhabitants perished in the disaster while the famous law school vanished under rubble.
Eastern Roman Berytus shrank to village size by 635 CE when Arab forces conquered it. The population had become fully Christian and Hellenised before this event which weakened defenses and accelerated the fall of the once-great colony.
Excavations between 1995 and 1997 uncovered ruins of ancient Roman Baths on the eastern slope of Serail Hill. A landscaped public space called the Garden of Forgiveness now covers these remains with low-slung glass walls designed by British landscaping firm Gillespies.