Whether or not you like maps, if you're in Boston, you should see this exhibit.
The Boston Public Library's Norman B. Leventhal Map Center has an incredible exhibit of New England maps, "Boston and Beyond: A Bird's Eye View of New England." All of the maps are realistic in that every street and building is actually drawn for a bunch of New England towns (the exhibit focuses on Boston, but most major New England cities are covered). It's remarkable to see the pre-'fill-in' maps of Boston: I figure I live what was once about 200 yards offshore.
It's a nice weekend (for Boston in January). Head on over to the Boston Public Library (at Copley) and check this out. And like everything else at the library, it's free (and open on Sundays too).