An area 12,300 years in the making, Niagara Falls is a natural wonder unlike any other. The history of Niagara Falls goes back thousands of years, to the Ice Age, when large torrents of water were released from the melting ice, draining into what is now known as the Niagara River.

No, Niagara Falls is a natural waterfall, but it is one of the most "human-managed" natural wonders in the world. The falls were formed naturally about 10,000 years ago during the retreat of the Wisconsin glacier at the end of the last Ice Age. However, the appearance of the falls today is heavily influenced by human engineering. To prevent the falls from eroding away (which they were doing at a rate of 3 feet per year), the US and Canadian governments installed underwater weirs and redirected a significant portion of the river's flow—up to 50% or more depending on the time of day—into massive tunnels for hydroelectric power generation. In 1969, the U.S. Army Corps of Engineers even "turned off" the American Falls by building a temporary dam to study the rock face and remove debris. While the water is natural, the volume you see is a "controlled" spectacle designed to balance tourism, conservation, and the power needs of millions of people.