Short answers, pulled from the story.
Alexandria was founded in April 331 BC by Alexander the Great, after he captured Egypt from the Persians. He chose the site envisioning a causeway to the island of Pharos that would create two natural harbours, then left Egypt a few months later and never returned.
The Lighthouse of Alexandria, built on the island of Pharos, stood approximately 138 metres high and was constructed mostly of solid limestone with a furnace at its top. Ptolemy I began the project and Ptolemy II Philadelphus completed it at a total cost of 800 talents after 12 years of construction. It was destroyed by an earthquake in the 14th century, making it the second-longest surviving ancient wonder after the Great Pyramid of Giza.
The Great Library of Alexandria is generally thought to have been founded at the beginning of the 3rd century BC during the reign of Ptolemy II. The library faced destruction during Julius Caesar's siege of Alexandria in 47 BC, though the full details of its losses remain contested. The modern Bibliotheca Alexandrina was inaugurated in 2002 near the site of the original library.
Alexandria had a population of 6,100,000 in 2023. It is Egypt's second-largest city after Cairo, the largest city on the Mediterranean coast, and the sixth-largest city in the Arab world.
Alexandria sits on the Nile river delta, making it one of the most vulnerable cities in the world to sea level rise. The 2022 IPCC Sixth Assessment Report estimated that by 2050, Alexandria could bear roughly half of the cumulative damages projected for twelve major African coastal cities, with costs ranging from tens of billions to over a hundred billion US dollars depending on the emissions scenario. Research published by the American Geophysical Union found that rising groundwater levels are already corroding building foundations, with more than 7,000 buildings predicted to be at risk of collapse by 2025.
Alexandria was a major centre of early Christianity and hosted the Patriarchate of Alexandria, one of the leading Christian institutions in the Eastern Roman Empire. Until 430, the Patriarch of Alexandria ranked second only to the bishop of Rome. After the Council of Chalcedon in AD 451, the Alexandrian Church split into the Miaphysites, who became the Coptic Orthodox Church, and the Melkites, who became the Greek Orthodox Church of Alexandria.