Since its first publication in 1976, this guide -  with nearly thirty thousand copies sold - has become the standard book for exploring the twenty-six counties of western Pennsylvania.  Yet in the past fourteen years, many sites have been lost through fire, demolition, or neglect - and many other sites of historical interest have been discovered and documented.  Now Helene Smith and George Swetnam have completely revised the text, updating the capsule histories, the site descriptions, and location directions (including all the new Pennsylvania road numbers), and adding several hundred new entries.