Google earth supplies an astonishing amount of anomalous constructions in North America. Large and small and inspiring many of them are located some 15ft below the present day sealevel. This is very much Michael Tellinger type stuff in that evidence hidden from us all at ground level is starkly visible from the air . You'll be fascinated, and once again it lends credence to the concept of a sophisticated civilisation around the world before the great flood aknowledged by mainstream archaelogy about 7500BC.