There are always plants and trees in bloom at the National Arboretum, so nature-lovers will enjoy taking a break from the city noise to wander through the tranquil grounds of this “living museum”. The 446-acre campus is open to cars, bicycles, and foot traffic, and guided bus tours are also available for groups of 10 or more. If you only have time to visit a few areas, don’t miss the National Bonsai and Penjing Museum or the aquatic garden and koi pond.