Olmsted’s challenge was to restore a saltwater marsh to ecological health. Devoting himself to combining landscape transformation with sanitary engineering, he turned a fowl-smelling tidal creek and swamp that periodically flooded into "scenery of a winding, brackish creek, within wooded banks; gaining interest from the meandering course of the water."   The Fens, like all landscapes, has changed over time. The damming of the Charles River (1910) turned it into a freshwater marsh. Noted landscape architect Arthur Shurcliff added new features such as the Kelleher Rose Garden and ballfields, employing the more formal landscape style popular in the 1920s and 1930s.   Within the Fens exists the oldest remaining wartime “Victory Garden” (1941) planted by citizens. Today, it is a well-loved and tended community garden of flowers and vegetables.