At night the Niagara Falls are illuminated by lights; sometimes bright white, sometimes different colors, always changing.
Interestingly (to me), the water's rate of flow is strictly controlled. At night there is less water allowed over the falls; during the day, they allow more water for more spectacular viewing. The rest of the river's flow is directed into the power generating station downriver, bypassing these falls. The slower rate of flow also helps slow the rate of erosion, preserving the scene for generations.
About 10% of the Niagara Falls flows over the American Falls and Bridal Veil Falls on the U.S. side. The other 90% flows over the Horseshoe Falls on the Canadian side.