In 1969, Niagara Falls was reduced to a trickle. The U.S. Army Core of Engineers, worried about erosion and the pile of rocks at the base of American Falls, one of the three cascades that make up the tourist attraction, built a temporary dam upstream. They strengthened some faults they found, but also uncovered the remains of two people—a man and a woman—and oodles of coins tossed over the falls by visitors. 

Niagara Falls is a stunning natural wonder, but there are plenty more hidden secrets to discover when the onrush of water becomes a little too much. From the role of the region in the Underground Railroad to paired statues of electrical pioneer Nikola Tesla here are some of our favorite surprises to seek out on a visit to this Ice Age marvel.