The major airport that services the city of Philadelphia is Philadelphia International Airport.  It is readily accessible from all of the major highways, and only about fifteen to twenty minutes from the heart of the city's bustling downtown.  Philly International is located at 8900 Essington Avenue, just off of Interstate 95 south or Interstate 76 from the east.  Convenient directions can be found below:

 

From Center City Philadelphia:
I-95 South to the Philadelphia International Airport Exit
or
76 East following signs for the Philadelphia International Airport

From the PA Turnpike:
Take the PA Turnpike to the Mid-County Exit (Route 476)
Take 476 South (Chester) to Interstate 95 (I-95)
Take I-95 North to the Philadelphia International Airport Exit

From the NJ Turnpike:
Take Exit 3 to the Walt Whitman Bridge
After the toll plaza stay in the far right lane and take I-95 South
Follow I-95 South to the Philadelphia International Airport Exit

From Delaware:
Take I-95 North to the Philadelphia International Airport Exit

Travel to and from the airport is designed to be easy and hassle-free, with various limos, taxis, and even the city's public transit all available to you.  SEPTA offers a $5.00 one-way train to Center City, for example, so you can be whisked directly to or from your hotel.  Buses also run from the airport to the city's lodging facilities; it's literally impossible to get stranded without a ride.