LandmarksWashington National Cathedral
A soaring neo-Gothic Episcopal cathedral, the sixth-largest in the world, famed for its stained glass (including a "Space Window" with a lunar rock), gargoyles, and a 30-story central tower. Go to escape the Mall crowds for a quieter, architecturally stunning landmark in a leafy uptown neighborhood. A ticket is required for sightseeing tours; worship and private prayer are always free, and hours vary by day, so check ahead.