Olmsted Plan, 1887
“Back Bay - Scenery of a winding, brackish creek, within wooded banks; gaining interest from the meandering course of the water; numerous points and coves softened in their outlines by thickets and with much delicate variety in tone and color through varied, and, in landscape art, novel, forms of perennial and herbaceous growths, the picturesque elements emphasized by a few necessary structures; strong but unobtrusive.” -- Frederick Law Olmsted, 1880.
Image: Frederick Law Olmsted National Historic Site 
Island at Avenue Louis Pasteur, 1905
In 1909, a few years after this photo was taken, the Museum of Fine Arts relocated to the southeast side of the Fens on Huntington Avenue. Then, in 1910, the Charles River Dam was completed, transforming the original saltwater marsh into fresh water.
Image: Boston Public Library 
Becoming a 20th Century Park
From 1910-1920, the design of the Fens reflected the work of the Olmsted brothers with landscape architect Arthur A. Shurtleff (Shurcliff). They worked on the park from 1910 up into the 1930s, turning it from a salt water fens into a 20th century park.
Image: Marion Pressley 
Revised Plan, 1921
Shurcliff turned the focus of the park to the Museum of Fine Arts, with a formalized lagoon reflecting the museum. He added the Rose Garden and incorporated Clemente Field, a recreation area. In 1924, Shurcliff also designed the Charlesgate East and West connection at Commonwealth Avenue where the Olmsted Park system connects to the Charles River basin at Commonwealth and Beacon Street.
Image: Frederick Law Olmsted National Historic Site
The Fens Today
In the lower basin, you can see the Rose Garden, WWII-era Victory Garden, and War Memorials.
Image: Alex Maclean / Landslides
Rose Garden
The rose garden was designed by Arthur A. Shurcliff in 1931.
Image: Marion Pressley 
Music in the Rose Garden
Image: Margaret Dyson / Boston Parks and Recreation 
Victory Gardens
In 1942, the Victory Gardens were added. They are still thriving on filled land on the northwest side. Adjacent to the Victory Gardens, memorials for the Korean War and Vietnam War were later added.
Image: Marion Pressley 
Agasszi Bridge Shelter (Duck House)
This bridge shelter is a remnant from the original Olmsted design.
Image: Marion Pressley 
Agassiz Bridge, 1911
Image: Emerald Necklace Conservancy 
Recreation Area
Image: Marion Pressley 
A Crossing for People and Geese
Geese are a major problem in the Necklace. They even know how to cross with the red lights.
Image: Marion Pressley