If you have out-of-town guests visiting you in DC, be sure to have them take the Old Town Trolley tour. The trolleys have pickup spots all over DC, and you can hop on and hop off at every place. The trolley takes you through great areas of the city - the Mall, Embassy Row, the National Cathedral, the zoo. Plus, you can send your guests out for the day and know they'll be taken care of in case you can't check out the sights with them.
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