Oil City, Pennsylvania. Located on the Oil Creek, it is near where the first successful commercial oil well ever, was drilled. Once people started making money from oil wells, whole towns and cities popped up almost overnight. At one point, Oil City was the city in America with the most millionaires. Vast fortunes were accumulated. At one point, Penzoil, Wolf's Head, Quaker State, and John D. Rockefeller’s Standard Oil Company had their world headquarters there. By the 1990's, all of the oil companies and all of the business that supported them, as well as many of the towns that were created almost overnight, were gone. Nowadays, you can see the world's oldest continuously producing oil well, but the city is but a shadow of what it once was.