Boston's flagship outlet of Commonwealth Books has moved, from the old location on Boylston Street to 9 Spring Lane, just off Washington Street near Downtown Crossing (just steps away from their other shop under Old South Meeting House, and very close to both the State Street and Government Center T-stops).
The new shop is now open for business, and if you're in the area, I strongly encourage a visit. The space is absolutely beautiful, with plenty of room for browsing (this space is about the same square footage on one floor as the old shop had on two), a really elegant layout, and the usual fine stock of good books.
Stop by and say hello!