This $28 tour is worth every dollar spent. A huge thumbs up goes to the incredibly knowledgeable guides, who are more interesting than any history professor I've ever had. (They don’t ask for tips, but they’re so good that it can be hard not to give them anything.) It is advertised as a 90-minute tour, but that’s if you don’t get off the little bus. It stops at various locations throughout Lexington and Concord, including historically significant buildings, the National Heritage Museum, and Minute Man National Historic Park. You can get off at various stops for 90 minutes each, at the end of which a bus will stop by so you can hop on again. It’s a great tour because you can get on and off when you like, so you can do your own exploring. At the same time, you've got knowledgeable guides explaining the sights. I’d suggest planning on spending several hours on this tour.