After college, I lived in Boston for a few years. For me, one of the highlights of living there was the wonderful libraries, especially the Boston Public Library Central Library in Copley Square. For more on this wonderful building, here is the library's information page and here is the Wikipedia entry. (Photos from Wikipedia, unless otherwise noted.)
There are two parts to this wonderful building - the historic library designed by McKim, Mead & White and the modern section by Philip Johnson. The Johnson building is very utilitarian in appearance, especially in comparison to the McKim building, but houses an amazing collection. When I lived there, I loved to wander around the stacks, pick up a few books, then head into the McKim section to find a place to read. In good weather, I would find myself in the courtyard.
A view after its restoration, from the BPL website:
In cold weather, I'd try to find a seat in one of the reading rooms. Sadly, I never got to use this one, Bates Hall:
I visited the BPL about once a week when I lived in Boston, more sometimes in good weather, as I loved to walk there after work, browsing until it got dark, then hopping on the T to head home for dinner.