If you have time, check out the Freedom Trail. It does involve walking around Boston but you can do as little or as much of the trail as you'd. There's so much history right in Boston!
If you love the history of the Witch Trials, Salem is the place to visit. Many museums and shops to explore. Just be sure to buy tickets in advance for some of the more popular museums.
If you're a baseball fan or big sports fan look up options for a guided Fenway Park Tour, home of the Boston Red Socks.