The National Arboretum, one of Washington’s best-kept secrets, is home to 9 miles of winding parkland roads covering more than 450 acres. Step outdoors and enjoy a spring day there during what is usually the peak blooming time for azaleas, dogwoods, and seasonal wildflowers. The visit includes a walking tour of popular collections, a picnic box lunch on site, and a special guided tour of the National Bonsai & Penjing Museum.