Alexander's Oikoumene was the dream of the Great Stratelates, who wanted to assemble a new empire, that would incorporate all the nations in one unified and ‘civilized’ world, that would be ruled after him in justice. Within this context, Egypt would be part of Alexander’s Oikoumene, while Alexandria would be the window of Egypt to the Mediterranean as a major port. Alexander never experienced the city during his lifetime. It was Ptolemy son of Lagos, the companion of Alexander and first king of Hellenistic Egypt, moved the capital of Egypt from Memphis to Alexandria. Its street plan was based on the typical Hellenistic Hippodamian system with a rectangular shape, and it was divided into regular boxes. This city planning common in all Greco-Roman world, allowed the expanding of the cities in a rational and functional way. The city was endowed with great works, representative of the advanced engineering knowledge of that time. The legendary works were the Heptastadion, the Pharos Island and the Lighthouse. Strabo and Diodorus describe with admiration the glamorous city that had all the common edifices of the hellenistic and roman type. The palace Quarters, the palace complex of the Greek pharaohs of Alexandria, the city center with the gymnasium and the law court, the Dikasterion. The cityscape of Roman Alexandria was adorned like other cities of the Hellenistic East with colonnades, tetrastyles, fountains, city gates and triumphal arches, Theater -Odeon, baths, forum, villas with splendid mosaics and the Sarapeion, the Acropolis. The study continues with the meaning of the Harbor of Alexandreia that gave to Egypt an important political influence role in the Mediterranean especially in the Middle and Late Roman period. The role of Alexandria as the capital of economy continued even after being part of the Roman Empire and later during its division. Alexandria lost its independence but remained one of the most important ports in the Mediterranean. The next chapter of the study deals with the famous Library of Alexandreia, reference for all intellectual world. There is no doubt that the greatest intellectual achievement of Hellenistic Alexandria and her Hellenistic Kings was the Great Library and the Museum. These were the first institutions to deal with knowledge and understanding the “other” from a universal point of view. The life of these institutions is marked by the librarianship of the major Greeks scholars Zenodotus, Callimachus and Apolonius of Rhodes and Eratosthenes, and the relations with the great personalities such as Euclide, Eratosthenes, and Eudoxis of Cnidos in mathematics; Archimides in applied science; Calimachus, Apolonius of Rhodes, Aristophanes of Byzantion in literature; Praxagoras of Kos in medicine, Ctesibios of Alexandria, Herophilus, the leading Alexandrian physician, Aristarchus of Samos, Hypatia and many others. The name “School of Alexandria” was applied to both the philosophical trend and the most important figures of philosophy who worked in Alexandria.