The National Park Service is bringing interpretive bus tours back to the National Mall in Washington, D.C. Last week, Open Top Sightseeing added a National Mall route for its familiar double-decker buses. The route has more than two dozen stops, including the Capitol, Smithsonian museums and major memorials. Visitors will be able to hop on and off throughout the day. Tickets are $32 for adults and $20 for children. Children younger than 5 are free.