Using engineering genius the Venetians — refugees from nearby towns seeking shelter from Visigoths and later Attila the Hun around 500-550 AD — turned a series of swampy islands into a real city and then into the global center of commerce by the 9th century, well before the time of Marco Polo in the late 13th century.
https://youtu.be/77omYd0JOeA?si=QcsfQ_SwjlqkKk0H
As the population grew they encountered the usual problems with growing cities — fresh water and waste disposal — and once again employed engineering genius to solve them in simple, effective and efficient ways.
Venice was the capitol of the Republic of Venice, for 1100 years a global power until conquered by Napoleon in 1797.