Great Meadows National Wildlife Refuge (NWR) is located just 20 miles west of Boston. The refuge was established in 1947 to provide nesting, resting, and feeding habitat for migratory birds. Roughly 85 percent of the refuge's 3,600 acres is comprised of valuable freshwater wetlands stretching along 12 miles of the Concord and Sudbury Rivers. Well known for its birdwatching opportunities, the public can also enjoy a variety of other wildlife-dependent recreational activities while visiting the refuge. <P>Refuge landscapes inspired the thoughts of such storied environmental philosophers as Henry David Thoreau and Ralph Waldo Emerson. More than a century and a half later, summer recreationists sun themselves along the shores of nearby Walden Pond -- now protected as a state park. Paddling through the refuge along the Concord River, canoeists may pass below the Old North Bridge -- the site of America's birth that is now managed by Minute Man National Historical Park. <P>