Parks & Gardens in Boston, Mass.

Thanks to Frederick Law Olmstead, Boston's "Emerald Necklace" of parks is a living treasure.

Commonwealth Avenue, Boston MA

Commonwealth Avenue, a parklike boulevard that's part of Boston's Emerald Necklace.

Boston Common, one of the country's oldest public parks

Public Garden, the flowery formal counterpart to the Common

The "Emerald Necklace," Frederick Law Olmstead's system of parks and verdant thoroughfares

Arnold Arboretum, Boston's "living collection" of plants from around the world