From NYC / New Jersey Turnpike:
From the N.J.Turnpike take exit #4 to Rt. 73 north. Go about 1 mile and get onto Interstate 295 heading south. Go 2 miles and exit at #34B onto Rt. 70 west: Camden/Cherry Hill (big road, 2 lanes each way). You'll pass Rt. 41, go a few more miles and you'll see signs for Phila. and the Ben Franklin Bridge. You will have to merge to the right at least once to stay on the road that takes you to the Ben Franklin Bridge. The signs make it all very clear. This section on Rt. 70 from I-295 to the Ben Franklin Bridge is 7.7 miles. It gets uglier as you go...see directions below.

From the Ben Franklin Bridge / I-676 West (Vine Street expressway):
Go over the Bridge ($3 toll, free coming back -"EZPass" is accepted) and stay in the center/left lanes to follow signs to Interstate - 676 West. As you come to a light, the road will go from 6 lanes to 2 lanes and then 1 lane that is the entrance to I-676 West. Take I-676 West a mile or two to the end, bearing right to exit onto I-76 East (the signs will also say "International Airport"). The road makes a hair-pin turn to the left and the first exit you can get off on is "Market Street / 30th Street station". The next exit is ON THE LEFT and it says "South Street". Take the exit ramp (up) to a traffic light and turn right. This is technically "South Street" but there may not be a sign. Go through the first light and at the 2nd light, the road bends a little to the left and is now called "Spruce Street".

Parking:
You can either head up Spruce Street and try to find a parking place or you can turn right at that 2nd light (33rd Street) and find parking there. If you go up Spruce, be aware that there are no cross streets until 38th Street due to the Penn Campus. It is a 2-way street so you can try to do a U-turn and come back to 33rd Street and turn left. If you go down 33rd Street, there will probably be parking. There are also 2 lots on the right side of 33rd Street. The first one is private and there is a sign that says: "Permit Parking"; the 2nd one is public - park there. The cost is $8 before 9PM (maybe you can negotiate) or free after 9PM. Walk back to Spruce Street and up to Houston Hall: on the right between 34th & 35th Streets.