There are two museums at For Stanwix: One inside the fort, and one here in the Visitor's Center. I surrendered myself to the authorities, in the person of a friendly Ranger, and asked if he wanted my money. "Did you pay taxes this year?" he asked. Why yes I had, so I had already paid for my admission to the fort, and his salary! Which is my long-winded way of saying that entrance to Fort Stanwix National Monument is free, whether you've demonstrably paid your taxes or not.