What was the Istanbul called before the ottomans conquered the city in the 15th century

Answer:

Seen against the background of the millennia, the fall of the Roman Empire was so commonplace an event that it is almost surprising that so much ink has been spilled in the attempt to explain it. The Visigoths were merely one among the peoples who had been dislodged from the steppe in the usual fashion. They and others, unable to crack the defenses of Sasanian Persia or of the Roman Empire in the East (though it was a near thing), probed farther west and at length found the point of weakness they were seeking on the Alps and the Rhine. The complicated political relationship existing between France and England in the first half of the 14th century ultimately derived from the position of William the Conqueror, the first sovereign ruler of England who also held fiefs on the continent of Europe as a vassal of the French king. The natural alarm caused to the Capetian kings by their overmighty vassals, the dukes of Normandy, who were also kings of England, was greatly increased in the 1150s. Henry Plantagenet, already duke of Normandy (1150) and count of Anjou (1151), became not only duke of Aquitaine in 1152—by right of his wife, Eleanor of Aquitaine, recently divorced from Louis VII of France—but also king of England, as Henry II, in 1154. A fresh complication was introduced when Charles IV died on February 1, 1328, leaving no male heir. Since there existed at that time no definitive rule about the succession to the French crown in such circumstances, it was left to an assembly of magnates to decide who ought to be the new king. The two principal claimants were Edward III of England, who derived his claim through his mother, Isabella, sister of Charles IV, and Philip, count of Valois, son of Philip IV’s brother Charles.