Something you might not know about the Cathedral is it is not part of the federal government.  It is a active Episcopal church.  Something else is that the church is nowhere near the "core" area of D.C. down around the monuments and such.  It is a good ¾-mile hike from the nearest Metro stop (Cleveland Park, Red Line).

Nonetheless the National Cathedral is an incredible church building.  We spent quite sometime wandering around taking it all in.