The USA, being such a large country practices geoengineering on a massive scale. This huge dam regulates the Colorado river, thus halting the evolution of the Grand Canyon which lies just downstream.
The wilds of Glen Canyon used to lie upstream, but it is now a lake that people fish in.
In order to see this view you have to go through a silly security procedure, and promise not to mention the dambusters during your guided tour. I think this may be counterproductive. I doubt it would occur to most people to suppose that a dam needs protecting from visitors' handbags, but if a handbag is really all it takes to bring the whole thing down, people may be tempted to try.
Up there is the visitor center.