The locations of various settlements and cities can completely change the outlook of a civilization. History can be determined by the strategic tenability of a particular city. Is it close to key resources that few allies or adversaries possess? Is it defensible? Are the people wealthy or poor? Is there a port for increased commerce and economic prosperity? All of these aspects matter, and more.
Ephesus was one such key location of the Byzantine Empire. It was an important bastion of tourism for centuries before the empire even came to be. The Temple of Artemis was built there. Because of what it represented to the western Romans — prestige, power, etc. — many foreign powers sought to dominate it. It was finally taken by Arabs in 668 A.D. and burned to the ground. They continued onto Constantinople.
Constantinople was always destined to become the capital of the Eastern Roman Empire. An imperial palace was built there to house the emperors. Wealthy citizens of the empire sought to live there. It was surrounded by tall walls that would become the target of attack for centuries — but they managed to stay standing for around 800 years. It was sacked during the Fourth Crusade in 1204 A.D. before being brought back into the empire in 1261. It was once again stormed and destroyed — for the last time — by the Ottomans in 1453.
Alexander the Great built Alexandria around 330 B.C., and would remain important to the Mediterranean region for a thousand years. Some believe that it was the most populous city to reach over 100,000 people. Alexandria was very important to Christians while the religion was still in its first stages. Alexander was entombed there, and many pilgrims visited his burial site. Alexandria’s importance declined when Paganism was outlawed by Theodosius in 391 A.D.