The first answerer is right for modern cases. However, historically, Washington Square was the Potter s Field for the City. Although this is no longer the case.http://www.ushistory.org/tour/tour_washs��http://libwww.library.phila.gov/explore/��
It s not necessarily for the poor and convicts, it s for bodies that are unclaimed, no matter who they are. As far as I can tell, it s at the city s Medical Examiner s Office because the remains are cremated, not buried.