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.
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.