The Back Bay is a
Boston neighborhood bordered by the
Charles River on the north, downtown and
Beacon Hill to the east, the
South End to the south, and the
Fenway to the west.
The name refers to the fact that the area really was a bay at one point (a putrid marsh, more accurately) -- the whole area was filled in during the late nineteenth century. As a relatively late addition to Boston, the Back Bay has the strange distinction of being laid out on a grid, in stark contrast to the winding streets of downtown Boston.
Commonwealth Avenue, which runs through the center of the Back Bay, was modeled after the Champs-Élysées in Paris and features a long park down the middle. It's part of Boston's Emerald Necklace.