Talks will take place in Levine Hall, room 101 (Wu and Chen Auditorium). Levine is located on Walnut St between 33rd and 34th. Please use the entrance to Levine marked (2) on this map. (This entrance faces Chancellor Walk, a pedestrian pathway south of Walnut street on the west side of the building.) Make sure that you use this door. Not only is it right by the lecture hall, but other entrances require card access.
Philadelphia is easy to reach by both car and train. (If you have both options and you're trying to decide which to use, I definitely recommend the train -- 30th St. Station is an easy 15 minute walk from the department.) Travel instructions, maps, and locations of nearby parking garages can be found here: http://www.cis.upenn.edu/departmental/visiting.shtml