Ghost Hunters - Season 6 Episode 12 America's First Zoo
Overview: The Philadelphia Zoo is the oldest in the country, but the reported Native American burial ground beneath it is even older. While there are no claims of animal ghosts, there are reports from the staff of disembodied voices, footsteps, apparitions and faces peeking through windows and misty shadows. There are 5 buildings to investigate, so the team has its hands quite full.