Bozeman's Museum of the Rockies is a Montana treasure. If it's been a while since your last visit, here's some awesome stuff to check out at MOR Free Day, Feb 25.
Heraclitus must have had Montana in mind when he wrote, "everything changes and nothing remains still; and you cannot step twice into the same stream." Sounds about right, especially if you've lived in and around Bozeman for at least 20 years.