When William Penn designed the City, he called the main East-West thoroughfare High street, but they renamed it Market Street because of the open air markets that built up along the street as it came away from the Delaware River.  As time progressed the market was moved further down Market Street until in the late 1800s it became so noisy and dirty that the City decided to move it indoors to the Reading Terminal Market, within the station building, in 1892. So when you're on your Philadelphia walking tour, you’ll understand that it’s actually as old as the City!