Yeah, I am hoping to grab a pastrami sandwich for lunch at the Reading Terminal Market, so taking public transportation is something to consider. I’m not familiar with where to get on and off, however.
Philadelphia's main streets in center city are numbered when going north-south, and mostly names of trees when going east-west. The only exception on the major north-south streets is Broad Street, which was 14th street. The main east-west street is named Market Street.
The Reading Terminal Market is located at 51 North 12th Street. As you'll be driving,
CLICK HERE for instructions for how to get there via car.
You basically have a choice: do you park around the Reading Terminal Market and then walk to the Broad Street Subway, or do you park on/near Broad Street, and then walk from there to the Market, and then back to Broad Street to take the subway. It's 6 of 1, a half a dozen of the other. There isn't a perfect answer. There will be a lot more activity/people on Broad Street at night, so that is a consideration if you're not all that comfortable in a big city.
It's only a few blocks from the Market to Broad Street, so there really isn't much of a difference. If you elect to park on/near Broad Street, you probably should set your GPS for Broad & Walnut Street, and then park at one of the parking garages around there. If you elect to park at the Market, just follow the directions in the above link.
The Broad Street Line is a subway that runs under Broad Street. That's what you would take to and from the game from Center City. The stops in Center City that you should focus on are City Hall and Walnut-Locust. If you park at the Market, you'll walk from there to City Hall (located at Broad & Market), and take the subway south from there. If you park around Walnut Street, you'll either walk from the Market to City Hall (see the previous sentence), or after the Market trip walk around downtown and then either get on the subway at City Hall or at the Walnut-Locust stop.
If you park at the Market, after you're done just walk toward City Hall (Broad & Market). To add a little more confusion, there's a huge underground area around City Hall where you can access multiple transportation lines. You'll see entrances (stairs going down from the street) at most of the corners between the Market and City Hall. You can take any of them, and follow signs for the Broad Street Line (often in Orange, as it's also called the Orange Line).
In the event you walk around town after the Market, you can get to the subway at City Hall, or at the Walnut-Locust stop. (For Walnut-Locust, you can enter at Broad and Walnut, or Broad and Locust. Just look for the steps going down at those intersections, and make sure to get on the platform heading South.)
Regardless of which station you use, you will take the subway south to the AT&T station (the last station headed South). That's located at Broad Street & Pattison Avenue. Once there, you would follow the crowd to Broad Street, and you'll be able to see the Linc (Lincoln Financial Field) from there. It's a two block walk from the subway stop.
After the game, you'd get on the subway at the AT&T Station, and take the subway to either the Walnut-Locust station, or the City Hall station, depending on where you parked, and then walk to where you parked.
I probably made this more complicated than needed, but it's all the info you should need.