If my memory serves me right, (been a while since I’ve spent anytime in that particular area) that line runs along the Schuylkill River and used to be the old B&O line. 30th Street station is where that large smokestack is. 30th Street station was a stop on the old Pennsy commuter lines and and the terminus for their long distance passenger service. It has a rather large servicing yard just north of the station. That building behind the engines used to be the old Penn Fruit Building and and at one time housed a lot of Conrail offices.
(http://i253.photobucket.com/albums/hh58/rgseng/Philly01a.jpg)
The top of the picture is north. Starting from the bottom the streets crossing the river are South St,. Walnut St., Chestnut St., Market St. and JFK Parkway where the station is. The next crossing are commuter rail lines into Center City. The top crossing is the Vine St Expressway which ties into the Schuylkill Expressway just west of the river. The expressway is the gray line running along the river. The black line running parallel with the river is the elevated B&O line. The oval at the bottom of the pic is Franklin Field, where the University of Penna plays football. Their campus is to the left. The commuter lines are the dark line just to the left of the river and go underground at that large square building in the center of the picture below 30th st. Very interesting area right around there. That large square building is the US Post office and there used to be a Railway Express siding just below it.