Library of Alexandria in the context of "Greek diacritics"

Alexandria is a major city in Egypt. Lying at the western edge of the Nile River Delta, it extends about 40 km (25 mi) along the country's northern coast. It is Egypt's principal seaport, the second largest city after Cairo, and the largest city on the Mediterranean coast. Founded in 331 BC by Alexander the Great, Alexandria is one of the largest and most important cities of antiquity and a leading hub for science, culture, and scholarship.

Nicknamed the "Bride of the Mediterranean" and "Pearl of the Mediterranean Coast", the city is a popular tourist destination and a major industrial centre. It is the sixth-largest city in the Arab world and in the Middle East, and the eleventh-largest city and urban area in Africa. Alexandria was established originally near an ancient Egyptian settlement named Rhacotis, which later became its Egyptian quarter. The city was made the capital of the Ptolemaic Kingdom and became the foremost commercial, intellectual, and cultural centre for much of the Hellenistic age and late antiquity; at one time, it was the most populous city in the ancient world. Alexandria was best known for the Lighthouse of Alexandria (Pharos), one of the Seven Wonders of the Ancient World; its Great Library, the largest in the ancient world; and the Catacombs of Kom El Shoqafa, one of the Seven Wonders of the Middle Ages.

Egypt, officially the Arab Republic of Egypt, is a country spanning the northeast corner of Africa and southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to the north, Palestine and Israel to the northeast, the Red Sea to the east, Sudan to the south, and Libya to the west; the Gulf of Aqaba in the northeast separates Egypt from Jordan and Saudi Arabia. Cairo is the capital, largest city, and leading cultural center, while Alexandria is the second-largest city and an important hub of industry and tourism. With over 107 million inhabitants, Egypt is the third-most populous country in Africa and 15th-most populated in the world.

Egypt has one of the longest histories of any country, tracing its heritage along the Nile Delta back to the 6th–4th millennia BCE. Considered a cradle of civilisation, Ancient Egypt saw some of the earliest developments of writing, agriculture, urbanisation, organised religion and central government. Egypt was an early and important centre of Christianity, later adopting Islam from the seventh century onwards. Alexandria, Egypt's former capital and currently second largest city, was a hub of global knowledge through its Library. Cairo became the capital of the Fatimid Caliphate in the tenth century and of the subsequent Mamluk Sultanate in the 13th century. Egypt then became part of the Ottoman Empire in 1517, until its local ruler Muhammad Ali established modern Egypt as an autonomous Khedivate in 1867. The country was then occupied by the British Empire along with Sudan and gained independence in 1922 as a monarchy.

Eratosthenes of Cyrene (/ɛrəˈtɒsθəniːz/; Ancient Greek: Ἐρατοσθένης [eratostʰénɛːs]; c. 276 BC – c. 195/194 BC) was an Ancient Greek philosopher, polymath and scholar. He was known as a mathematician, geographer, poet, astronomer, and music theorist. Eratosthenes became the chief librarian at the Library of Alexandria. His work was the precursor to the modern discipline of geography, and he introduced some of its terminology, coining the terms geography and geographer.

He is best remembered as the first known person to calculate the Earth's circumference. He was also the first to calculate Earth's axial tilt, which similarly proved to have remarkable accuracy. He created the first global projection of the world incorporating parallels and meridians based on the available geographic knowledge of his era. Eratosthenes was the founder of scientific chronology; he used Egyptian and Persian records to estimate the dates of the main events of the Trojan War, dating the sack of Troy to 1184 BC. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers and composite numbers.

Ptolemy I Soter (/ˈtɒləmi/; Greek: Πτολεμαῖος Σωτήρ, Ptolemaîos Sōtḗr, "Ptolemy the Savior"; c. 369/68 BC – January 282 BC) was a Macedonian Greek general, historian, and successor of Alexander the Great who went on to found the Ptolemaic Kingdom centered on Egypt. Ptolemy was king and pharaoh of Ptolemaic Egypt from 305/304 BC to his death in 282 BC, and his descendants continued to rule Egypt until 30 BC. During their rule, Egypt became a thriving bastion of Hellenistic civilization and Alexandria a great seat of Greek culture.

Ptolemy I was the son of Arsinoe of Macedon by either her husband Lagus or Philip II of Macedon, the father of Alexander. However, the latter is unlikely and may be a myth fabricated to glorify the Ptolemaic Dynasty. Ptolemy was one of Alexander's most trusted companions and military officers. After the death of Alexander in 323 BC, Ptolemy retrieved his body as it was en route to be buried in Macedon, placing it in Memphis instead, where it was later moved to Alexandria in a new tomb. Afterwards he joined a coalition against Perdiccas, the royal regent over Philip III of Macedon. Perdiccas invaded Egypt but was assassinated by his own officers in 320 BC, allowing Ptolemy I to consolidate his control over the country. After a series of wars between Alexander's successors, Ptolemy gained a claim to Judea in southern Syria, which was disputed with the Seleucid king Seleucus I. He also took control of Cyprus and Cyrenaica, the latter of which was placed under the control of Ptolemy's stepson Magas. Ptolemy also commanded the construction of the Library of Alexandria and of the Lighthouse of Alexandria, one of the Seven Wonders of the Ancient World.

The Ptolemaic dynasty (/ˌtɒlɪˈmeɪ.ɪk/; Ancient Greek: Πτολεμαῖοι, Ptolemaioi), also known as the Lagid dynasty (Λαγίδαι, Lagidai; after Ptolemy I's father, Lagus), was a Macedonian Greek royal house which ruled the Ptolemaic Kingdom in Ancient Egypt during the Hellenistic period. Reigning for 275 years, the Ptolemaic was the longest and last dynasty of ancient Egypt from 305 BC until its incorporation into the Roman Republic in 30 BC.

Ptolemy, a general and one of the somatophylakes (bodyguard companions) of Alexander the Great, was appointed satrap of Egypt after Alexander's death in 323 BC. In 305 BC he declared himself Pharaoh Ptolemy I, later known as Sōter "Saviour". The Egyptians soon accepted the Ptolemies as the successors to the pharaohs of independent Egypt. The new dynasty showed respect to local traditions and adopted the Egyptian titles and iconography, while also preserving their own Greek language and culture. The Ptolemaic period was marked by the intense interactions and blending of the Greek and Egyptian cultures. Under the Ptolemies, Hellenistic religion was largely shaped by religious syncretism and imperial cult. Elements of Greek education became widespread in urban spaces, culminating in the foundation of the Mouseion (including the Library of Alexandria) and the Serapeum. During the Hellenistic period, the city of Alexandria, founded by Alexander the Great, would gradually surpass Athens as the intellectual centre of the Mediterranean world.

The Imperial Library of Constantinople, in the capital city of the Byzantine Empire, was the last of the great libraries of the ancient world. Long after the destruction of the Great Library of Alexandria and the other ancient libraries, it preserved the knowledge of the ancient Greeks and Romans for almost 1,000 years. A series of unintentional fires over the years and wartime damage, including the raids of the Fourth Crusade in 1204, impacted the building and its contents. While there were many reports of texts surviving into the Ottoman era, no substantive portion of the library has ever been recovered. The library was founded by Constantius II (reigned 337–361 AD), who established a scriptorium so that the surviving works of Greek literature could be copied for preservation. The Emperor Valens in 372 employed four Greek and three Latin scribes. The majority of Greek classics known today are known through Byzantine copies originating from the Imperial Library of Constantinople.

The Library of Celsus (Greek: Βιβλιοθήκη του Κέλσου) is an ancient Roman building in Ephesus, Anatolia, located near the modern town of Selçuk, in the İzmir Province of western Turkey. The building was commissioned in the years 110s CE by a consul of the Roman Empire, Tiberius Julius Aquila Polemaeanus, as a funerary monument for his father Tiberius Julius Celsus Polemaeanus, former proconsul of Asia, and completed during the reign of the Roman Emperor Hadrian, sometime after Aquila's death.

The Library of Celsus is considered an architectural marvel, and is one of the few remaining examples of great libraries of the ancient world located in the Roman Empire. It was the third-largest library in the Greco-Roman world behind only those of Alexandria and Pergamum, and is believed to have held around 12,000 scrolls. Celsus is buried in a crypt beneath the library in a decorated marble sarcophagus. The interior measured roughly 180 square metres (2,000 square feet).

The Mouseion of Alexandria (Ancient Greek: Μουσεῖον τῆς Ἀλεξανδρείας; Latin: Musaeum Alexandrinum), which arguably included the Library of Alexandria, was an institution said to have been founded by Ptolemy I Soter and his son Ptolemy II Philadelphus. Originally, the word mouseion meant any place that was dedicated to the Muses, often related to the study of music or poetry, but later associated with sites of learning such as Plato's Academy and Aristotle's Lyceum.

The Ptolemies reputedly established their Mouseion and Library with the intention of bringing together some of the best scholars of the Hellenistic world and to collect all the books known at the time. Although it did not imply a collection of works of art, the word mouseion is the root for the modern usage of the word museum.