what are some cheap fun things to do in and around boston/cape cod? serious answers only please, thanks!?

Take a historical tour of the city on the Freedom Trail. Very interesting and you'll learn a lot about some of the earliest history of our nation.

- Boston
Ride the T
Eat at Rock Bottom Restaurant
See what Navy ships are in port in South Boston
Walk the Freedom Trail

- Cape Code
Walk on the beach
Stay in your car while stuck in traffic

You can walk the Freedom Trail, or go to the beach at the Cape. Swan Boats downtown are only a few dollars and kids love it, if you have kids with you.

In Boston, nothing beats the Freedom Trail. A few of the stops along the way have an entrance fee, but most are free. Plymouth is also worth a stop, to see Plymouth Rock and the replica of the boat that they landed in. If you can afford to, I'd highly recommend taking a boat to Martha's Vineyard and then renting a car for the day and driving around the island.

To the north of Boston, there is the North Shore, which is very scenic with lots of small fishing villages.

Have fun!

Boston Pops
Nickerson Park
Nuntucket
Freedom Trail
Plymouth
No Name Restaurant
Copley Plaza
Mayflower
Salem
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There are so many things to do on Cape Cod that I can't even begin to tell you where to start. So I'm including a website from the Travel Channel for you to check out. Its written by real people about their experiences. You can see what they recommend (or not for that matter).

Some great responses already, so rather than rehash, I'll add a few more of my favorites.

There's also Salem (north of Boston),
visitng Bunker Hill memorial in Charlestown
visiting Old Ironsides (USS Constitution) in Charlestown,
JFK library (just south of Boston),
visit Lexington and Concord (where it all started) out Route 2.

You can also get a day pass for the "T" (subway) and ride all over just for fun!

Harvard Sq can be entertaining to walk around.

Or you can bounce down to MIT and walk those hallways as well. Next to that is the esplanade, where you can walk the Charles River, which is gorgeous in the summer time, walk downtown and grab something to eat near fanueil hall!

For affordable seafood though, I agree. No Name's is the place to go!