Amnesty International Philadelphia meets Jan to Oct every 4th Thursday (Nov and Dec, every 3rd Thursday) at 1906 Rittenhouse Square, Philadelphia, PA 19103, which is a small building owned by the Ethical Society.
From NJ: PATCO to 16th and Locust, walk west one block to Rittenhouse Square, walk 3/4ths through the park, the building is on the left across the street.
From West Philadelphia: buses, trams down Chestnut or Market St, get off at 20th Street, walk south the Rittenhouse Sq. Or walk east down Walnut Street.
Driving? Ugh. Some parking garages are around.