U.S. National Arboretum

"Technically a research division of the Agriculture Department, this 446-acre haven always has many more trees than people, even on its busiest days during the spring azalea season." Full review

"Take a break from the cityscape with a visit to the U.S. National Arboretum, where you can stroll through its azalea gardens, tour the National Bonsai and Penjing Museum." Full review

"This 446-acre site has specialty gardens, the former U.S. Capitol columns, the Arbor House Gift Shop and the National Bonsai & Penjing Museum." Full review

"One of the largest arboretums in the country, this federally owned 446-acre tract situated on the gentle slopes of Mount Hamilton provides a tranquil respite from the warehouses and thoroughfares of surrounding northeast Washington" Full review

"This 446-acre oasis operated by the U.S. Department of Agriculture is a blaze of color. In early summer, clematis, peonies, rhododendrons, and roses bloom...the arboretum has guided hikes." Full review