This is another park I’d visited when I was a kid because my aunt and uncle live nearby. It’s really fun to wonder around with kids. I went with my cousin and her three oldest boys (the oldest I think was seven at the time) several years ago, and watching them wander through the fort was a a ton of fun.
The other feature of this park is the observatory at the top of the Penobscot Narrows Bridge. It does cost more than the standard park entrance fee, but if it’s a nice day, it’s worth the extra price.