Took a road trip out west and along the way we happened upon an extinct volcano in New Mexico. There are active, dormant and extinct volcanoes and you can visit a number of them. Here is a list at 10 Volcanoes You Can Walk On. Brian, my traveling partner, and I discovered
Capulin Volcano which is managed by the National Park Service. I'm sure it's tame as far as volcano hikes go, but it is an easy hike and there are no special precautions necessary to visit the volcano because it is extinct. You can visit the interior of the volcano and see lava left over from it was last active.