in the mid-1960s, James Rouse, a city planner, had the cool idea of not abandoning downtown Boston to decay, and instead building a marketplace that would attract tourists and keep workers downtown after dark. Fortunately he found Quincy Market and Fanueil Hall and began its transformation into what is now the most visited tourist destination in Boston.
Over the years it has become a little more commercial, Disney store, Ann Taylor, etc., but, even so, it is still a fun place to stop and arguably the best place to eat lunch in Boston. The Quincy Market building (in the center of Quincy Market) is a long hall of over the counter restaurants, at least fourty of them. It also has a comedy club on the second floor and a couple sit down restaurants underneath.
It is located a few minutes walk away from the docs where you can take harbor or whale watching tours. It's also not far from the Aquarium.