From walkthetown.com I think these have been freebies before.
Look Up, Central Park! New York City Walking Tours of the Upper East Side and the Upper West Side (Look Up, America!) by Doug Gelbert
Classic American Road Trips: Walking Tours of Towns along Route 66 (Look Up, America!) by Doug Gelbert
Classic American Road Trips: Walking Tours of Major League Baseball Teams on the West Coast (Look Up, America!) by Doug Gelbert
Look Up, Research Triangle! Walking Tours of 3 Towns In The Tarheel State (Look Up, America!) by Doug Gelbert
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http://www.amazon.co.uk/s/?url=searc...er=walkthetown
http://www.amazon.ca/s/?url=search-a...er=walkthetown