Food, Water, and the ability to defend, were the most important features in ancient cities. Corinth’s most important reservoir, the Fountain of Peirene, was fed from subterranean springs. It had a capacity of over 81,000 gallons.
Take a look at the horizon in the photo below. That was the level of the earth more than a century ago before archaeological excavations began at Ancient Corinth. The entire structure that we know as the Fountain of Peirene was covered with debris. This structure was built along the Lechaion Road which led from the Agora (Marketplace) to the Gulf of Corinth on the west side of the city.
The fountain is no longer in use, but if you walk close to the arches you can hear water flowing underneath the city.
Paul visited Corinth on his second journey (A.D. 50-53). In spite of obstacles that brought fear to the heart of Paul, the Lord assured him that He had many people in the city (Acts 18:10).
And he stayed a year and six months, teaching the word of God among them. (Act 18:11 ESV)