What makes this city remarkable in the English-speaking world is that it has kept its revolutionary geography almost intact. The 2.5-mile Freedom Trail threads through sites that are not reconstructions or museums of themselves, but the actual buildings where the events happened: the Old South Meeting House where Samuel Adams called the Tea Party; the Old State House from whose balcony the Declaration of Independence was first read aloud in Massachusetts; the Granary Burying Ground where Paul Revere, John Hancock, and Samuel Adams are still buried under the same headstones visitors can touch.

The USS Constitution's status struck me most in research. She is not a restored ship. She is not a replica. She is the same vessel, with the same naval commission, that last fired her guns in anger more than two centuries ago — and she is still crewed by active-duty US Navy sailors who live on board. The world's oldest commissioned warship, still in service. The sailors give you the tour.

The pairing of Day 2 surprised me too. The Museum of Fine Arts has one of the world's great Impressionist collections — and is a short walk from Fenway Park. Within 90 minutes you can go from standing in front of a Monet haystack to standing in the Red Sox dugout and looking up at the Green Monster. No other American city puts those two things so close together.