At 2 weeks post partum we took a trip to the Udvar-Hazy air and space museum. http://www.nasm.si.edu/museum/udvarhazy/ It is a GIANT airplane hanger full of restored planes from different eras; including the space shuttle. The girls were not as excited as we had hoped. Maybe after they have flown in more planes they will appreciate how cool it is. Even though this museum is not on the mall in down town DC, it is a must for airplane enthusiasts! James' friend who volunteers there took us for a private tour of the museum. He is a pilot and talked us through an air traffic control screen that they have up in a simulated air tower. You can see National airport and watch the planes take off while you are up there.