Does this airport have luggage lockers? I will have a long layover in Philly and would like to just leave my luggage at the aiport while I go to Center City. Where are these Lockers located? If there aren't any lockers, does anyone have a suggestion on where I can "leave" my luggage?

I cannot remember seeing lockers here but I'll bet there are some. Did you try the airport website or contacting them directly?
You can leave luggage in any of the US Air Clubs - a day membership rate is available.

In a post 9/11 world there are no lockers anywhere, and I would not leave luggage anywhere. Even the clubs do not let you leave luggage for an extended period of time.

Check with your airline and see if you can check the luggage through to your destination, so you won't have to carry it around.

All the lockers in every airport have been removed, for everyone's safety.

It depends on what a long layover is but if it's over 3 hours you might have time to go downtown, but anything less than 4 hours I would stay put, since you have to go through security again and that takes quite a bit of time.

Have a good trip.

You would think that all of the lockers have been removed but such is not the case. I just walked by quite a few lockers in Pittsburg last Friday. They were righ outside of my gate - I think in B.

All the airport lockers I've looked for since 9/11 are non-operational, as I'm sure they are at PHL too.

When I'm arriving at an airport and want to do some touring without luggage I always check by bags on the originating flight, and merely don't pick them up until I'm ready to. Of course my bag, going round and round the carousel all by itself is a candidate for theft, or maybe some inspection/destruction by an overzealous employee, but I'm willing to chance it, as I never have anything of value in the bag. The airlines BIGGEST risk was when that bag was up in the air, not sitting around the claim office in the airport. If you can risk the loss of your bags, consider doing the same as I do.