What's the easiest way to get from Old City to Italian market?
Will the Broad Street line take you there? If so, what are the stops?

Walking is actually the easiest way; it's not that far, and Philadelphia is very walkable. Otherwise, it would be the el (Market/Frankford line, heading toward 69th St, not the subway/Broad St. line) to 8th and Market and then the 47 bus on 8th street.

Depending on where in Old City you're talking about, walking to the 47 can be just a few blocks.

I agree with Amy; just walk it.

Thin

I also recommend walking -- but, JUST IN CASE you want to take mass transit, here's the info.

The Italian Market defines itself within this location:
http://italianmarketphilly.org/locations/

This pdf shows the route of the #47 bus, which goes right through the Italian Market area.
http://www.septa.org/maps/bus/pdf/047.pdf
Note that the Broad Street Line (aka "Orange Line") goes to "Ellsworth Federal" Station, which is also close to the area.

Of course, getting TO the Broad Street Line from Old City is a bit of a hike in itself; Broad St. is "14th" in order, and Old City is generally below 5th. In other words, you'd get to the 47 before you'd get to the subway.

Oh, in case I forgot -- you can ride the Market-Frankford Line (aka "Blue Line") from Old City, make a free transfer to the Broad Street Line at 15th Street \ City Hall Station, and then ride south to Ellsworth Federal.

But I still think walking is the best way.