The Mall contains the majority of the memorials in DC and is surrounded by the Smithsonian Museums - also, everything is free. (Not all Parking is free so plan to get there early and spend some $$ parking near the Mall). Also, wear walking shoes because it is a walk. There are plenty of food vendors selling food and water throughout the Mall. Though some people in my party complained about the walk, seeing all the history made it worth it. If you are not able to walk much, but tickets for the trolley tours (and to save time).
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