From the Flipkey article:

“We compiled a list of the top historical spots in each state worth traveling for. With this list, you’ll be able to plan a pilgrimage this year to see a gun fight in the Old West, sit in a centuries-old theater and listen to an opera, or tour a ship that sailed in the 17th century. Or maybe just schedule a little detour from what you already had planned, so you don’t miss out. These living legends embody the history and culture of their region, and you’ll be proud you stopped in when on vacation in any of the fifty states.” …read more.