In 1878, preeminent landscape architect Frederick Law Olmsted was commissioned by the City of Boston to manage a polluted wetland—once called the foulest in Massachusetts—at the edge of the then-new Back Bay neighborhood. Olmsted’s challenge for this project, which would later be called the Muddy River Improvement, was to clean and control this stagnant saltwater marsh, which regularly flooded the surrounding area. Combining landscape architecture with sanitary engineering, Olmsted’s efforts transformed the malodorous tidal creek and swamp into a scenic pool within wooded banks, deriving interest from the meandering course of the water. Olmsted renamed the area the Back Bay Fens. In 1910, the damming of the Charles River turned the Fens into a freshwater marsh. New plantings, including many trees, marked this transition. Over time, noted landscape architect Arthur Shurcliff added new features, such as athletic fields, and the Kelleher Rose Garden—employing the more formal landscape style popular in the 1920s and 1930s.