This series has five easy 5 minute installments. This first installment: Start With a Great Harbor.
Edward Gibbon is the gold standard of historians. When the Roman Emperor Constantine searched the empire for the perfect spot for a new capital city, he considered all aspects: strategic location; commercial advantage; easily defensible; transpiration hub; and more. Seldom in history was a site chosen with such deliberateness and with so much impact on world civilization as this one was. Truly, this is a first class event told by a first class historian.
This selection is from The History of the Decline and Fall of the Roman Empire by Edward Gibbon published in 1788. More information” section at the bottom of these pages.
Edward Gibbon wrote the definitive history of the Roman Empire.
Time: 330 AD
The unfortunate Licinius was the last rival who opposed the greatness, and the last captive who adorned the triumph, of Constantine. After a tranquil and prosperous reign, the conqueror bequeathed to his family the inheritance of the Roman Empire; a new capital, a new policy, and a new religion; and the innovations which he established have been embraced and consecrated by succeeding generations.
After the defeat and abdication of Licinius, his victorious rival proceeded to lay the foundations of a city destined to reign in future times, the mistress of the East, and to survive the empire and religion of Constantine. The motives, whether of pride or of policy, which first induced Diocletian to withdraw himself from the ancient seat of government, had acquired additional weight by the example of his successors and the habits of forty years. Rome was insensibly confounded with the dependent kingdoms which had once acknowledged her supremacy; and the country of the Czsars was viewed with cold indifference by a martial prince, born in the neighborhood of the Danube, educated in the courts and armies of Asia, and invested with the purple by the legions of Britain. The Italians, who had received Constantine as their deliverer, submissively obeyed the edicts which he sometimes condescended to address to the senate and people of Rome; but they were seldom honored with the presence of their new sovereign.
During the vigor of his age, Constantine, according to the various exigencies of peace and war, moved with slow dignity, or with active diligence, along the frontiers of his extensive dominions, and was always prepared to take the field either against a foreign or a domestic enemy. But as he gradually reached the summit of prosperity and the decline of life, he began to meditate the design of fixing in a more permanent station the strength as well as majesty of the throne. In the choice of an advantageous situation, he preferred the confines of Europe and Asia; to curb with a powerful arm the barbarians who dwelt between the Danube and the Tanais; to watch with an eye of jealousy the conduct of the Persian monarch, who indignantly supported the yoke of an ignominious treaty. With these views, Diocletian had selected and embellished the residence of Nicomedia: but the memory of Diocletian was justly abhorred by the protector of the Church; and Constantine was not insensible to the ambition of founding a city which might perpetuate the glory of his own name. During the late operations of the war against Licinius, he had sufficient opportunity to contemplate, both as a soldier and as a statesman, the incomparable position of Byzantium, and to observe how strongly it was guarded by nature against a hostile attack, while it was accessible on every side to the benefits of commercial intercourse.
Many ages before Constantine, one of the most judicious historians of antiquity had described the advantages of a situation, from whence a feeble colony of Greeks derived the command of the sea and the honors of a flourishing and independent republic.
The harbor of Constantinople, which may be considered as an arm of the Bosporus, obtained, in a very remote period, the denomination of the “Golden Horn.” The curve which it describes might be compared to the horn of a stag, or as it should seem, with more propriety, to that of an ox. The epithet of “golden” was expressive of the riches which every wind wafted from the most distant countries into the secure and capacious port of Constantinople. The river Lycus, formed by the conflux of two little streams, pours into the harbor a perpetual supply of fresh water, which serves to cleanse the bottom and to invite the periodical shoals of fish to seek their retreat in that convenient recess. As the vicissitudes of tides are scarcely felt in those seas, the constant depth of the harbor allows goods to be landed on the quays without the assistance of boats; and it has been observed that in many places the largest vessels may rest their prows against the houses, while their sterns are floating in the water. From the mouth of the Lycus to that of the harbor, this arm of the Bosporus is more than seven miles in length. The entrance is about five hundred yards broad, and a strong chain could be occasionally thrown across it, to guard the port and city from the attack of a hostile navy.
The geographers who, with the most skilful accuracy, have surveyed the form and extent of the Hellespont, assign about sixty miles for the winding course, and about three miles for the ordinary breadth, of those celebrated straits. But the narrowest part of the channel is found to the northward of the old Turkish castles between the cities of Sestus and Abydus. It was here that the adventurous Leander braved the passage of the flood for the possession of his mistress.
 The navigator Byzas, who was styled the Son of Neptune, founded the city 656 years before the Christian era. His followers were drawn from Argos and Megara. Byzantium was afterward rebuilt and fortified by the Spartan general Pausanias.
 The practical illustration of the possibility of Leander’s feat by Lord Byron is too well known to need particular reference.