A Virtual Tour of The Gardens at Dumbarton Oaks(site info)
A fully annotated "Slide-Show" presentation containing 50 screen-sized yet quick downloading images of the Gardens at Dumbarton Oaks, in the Georgetown section of Washington, DC. The garden was designed by Beatrix (Jones) Farrand between the early 1920s and the mid 1940s for Mr. and Mrs. Bliss. Cuirrently the gardens are owned by Harvard University.
http://GardenHomeArchitects.com/21-00-Virtual_Tour...
Arnold Arboretum(site info)
Manages a collection of hardy trees, shrubs, and vines located on 265 acres in Boston. The grounds were designed by Charles Sprague Sargent, in collaboration with the landscape architect, Frederick Law Olmsted.
http://www.arboretum.harvard.edu/