Niagara Falls. There's not a whole lot you can say about gigantic waterfalls. They are...ginormous. They are loud. And they are hard to get a decent picture of because of all the mist coming up! Regardless, I'm glad to say I've seen them.
These are the falls from the New York side. You can't actually get a decent shot of the Canadian side all rainbowed up at night. But while it's tacky, it's also awesome. I loved the rainbow falls!