Meteor Crater was formed by a meteor hitting the earth millions of years ago. It is not the largest crater on the Earth's surface, but it is probably the most impressive, because it is in the middle of a desert. It is a complete ring and is not covered with vegetation or water. The wind on top of the crater was intense. The crater is just east of Flagstaff. We were supposed to see the crater the evening before we got to the Grand Canyon, but we were late getting in and so we drove back after the canyon "on our way" to Las Vegas.
There was a cool old ruins and cars near the crater. Probably more left overs from the Route 66 days.
Right now, the only way past is to drive over the top of Hoover Dam. There was a checkpoint set up before we went over the dam - I thought it was part of the construction for the bridge and I made a joke to the guy about it being like a border crossing. He was not amused. I found out later that it is like a border crossing - Arizona and some of the other up-river states are very concerned that the dam could be subject to terrorism, and are very protective of it.
The new bridge they are building to bypass Hoover Dam. It will be ready in November 2010. It will give spectacular views of the Dam.