In Bedford, MA you can launch and park for free to start a trip up a slow moving river into Concord. On the sides, there are trees and bushes growing up out of the water, and if you are watching, you'll see turtles, beavers, and many different kinds of birds. There is a wildlife refuge on both sides with posted signs... great for nature watching.
Paddling up river, you will eventually reach the Minute Man National Park. You can beach the boats at the North Bridge where the spark of the American Revolution ignited a war, walk around or sit on a bench. There are Historians that will tell you all about it, as well as the start of literary revolution with a new Western philosophy called Transcendentalism. Ralph Waldo Emerson, Henry David Thoreau, and a few others lived in Concord.
Have lunch and sit back while the river drifts by and observe the beaver dams and turtles... you will come away with an idea of free thinkers and Americans.