Fodor's Expert Review Arnold Arboretum of Harvard University

This 281-acre living laboratory contains more than 4,000 kinds of woody plants, most from the hardy north temperate zone. The rhododendrons, azaleas, lilacs, magnolias, and fruit trees are eye-popping when in bloom, and something is always in season from April through September. The Larz Anderson bonsai collection contains individual specimens imported from Japan. In the visitor center there is a 40-to-1 scale model of the arboretum (with 4,000 tiny trees). If you visit during May, Lilac Sunday (usually held on Mother's Day) is a celebration of blooming trees, and is the only day picnicking is allowed in the Arboretum.