Survey - Where should we visit?

So, this post is just a simple question:  if you could tell visitors to your area about one place that they really should see, what would it be?  Think about the hidden gems that only the locals know about, or the one place that is just your favorite.  This could be a historic site, a park or attraction, a store or restaurant or museum, or even a hiking trail.  We're looking for some inspiration as we travel through different parts of the country, so post your answers or suggestions in the comments.  Don't post the obvious major attractions (i.e. The Alamo in San Antonio) unless that's really your favorite place in the area.