In this episode British art critic Andrew Graham Dixon is in Philadelphia exploring one of the world's most expensive books - John James Audubon's exquisite Birds of America. Also this week Andrew finds out about the wilderness that inspired America's greatest landscape painter, Thomas Cole. Later on Andrew uncovers the paradox at the heart of America: that progress and innovation have come at a tragic price, the destruction of the unique cultural heritage of Native Americans by European settlers. Andrew's journey takes us to the end of the 19th century and the announcement that the era of westward expansion was officially over. Show less