Visitor's Center 3001 Connecticut Avenue, NW Washington, D.C.
The Zoo's main entrance on Connecticut Avenue is easily accessible via the Metro Red Line.
Enter the Zoo grounds using the main pedestrian entrance, between the large lion sculptures. Proceed straight down the main walkway. The Visitor's Center is the first big building on your left. Auditorium is to the right.
or
You can find more visitor information, including parking rates, on the web site of the National Zoo.