Massachusetts National Cemetery has a memorial trail where, as of February 2005, 47 memorials and a carillon have been erected in memory of veterans from World War I to the modern era.
[Image via Google+]

This 30-foot Civil War monument was dedicated on May 30,1911 and during the ceremony, "Patriotic speeches were given including one by the keynote speaker, John F. (Honey Fitz) Fitzgerald, the Mayor of Boston and the grandfather of President John F. Kennedy. Mayor Fitzgerald spoke of the custom of various nations honoring their great generals, but said the United States was the one nation to recognize the common soldier in granite."
[Sandwich Historical Commission]

One of the oldest Civil War monuments in Massachusetts, the granite obelisk Soldiers' Monument was dedicated in July 1866 and is one of several veterans memorials on the green.
[CT Monuments.net]

Brewster honors veterans of Worls War I, World War II, the Korean War, and Vietnam with a series of monuments in front of the circa 1893 former Town Hall that now serves as the Council on Aging.
[CT Monuments.net]

On Chatham's Main Street green is this marble obelisk, a monument to the town's Civil War heroes. "Erected by the town of Chatham in memory of those that fell in the Rebellion of 1861 to 1865."
[CT Monuments.net]

Poor Orleans. First the Brits attack in 1814, then this: "On the warm morning of July 21, 1918 – during the last year of the First World War - a new prototype of German submarine surfaced three miles off the coast of Cape Cod, Massachusetts and attacked an unarmed towboat and her four barges. A handful of the shells fired by the U-boat’s two deck guns struck Nauset Beach, giving the modest town of Orleans the distinction of being the first, and only, spot in the United States to receive fire from the enemy during the entire World War." While there weren't any deaths reported, the bravery of responding citizens and armed service members is worth honoring.
[Attack on Orleans; Photo by Organic Photography]

Yes, the Pilgrim Monument was built between 1907 and 1910 to commemorate the first landing of the Mayflower Pilgrims in Provincetown on November 21, 1620, but the tallest all-granite structure in the U.S. is also Memorial Day-worthy: "The government retained the right to use the Monument during wartime. During World War I it was used as a lookout tower and later during World War II it was rumored the tower was used as a testing area for secret communications experiments. The government did not relinquish full control over the tower however until 1959."
[Fun facts & image via Pilgrim Monument, Provincetown Museum ]
[Wartime facts via iamprovincetown.com]

Ferrying over to the The Soldiers’ Memorial Fountain at Ocean Park in Oak Bluffs: "In August of 1891, Charles Strahan, a former Confederate soldier and publisher of the Martha’s Vineyard Herald, erected the memorial in honor of Union Civil War veterans." [Image via Town of Oak Bluffs]
[Quote via the Vineyard Gazette]

Last, but certainly not least, to Nantucket. The circa 1874 Civil War Monument in Monument Square is just one of a number of in-town dedications including the war memorials at the Town & County Building on Federal Street honoring Nantucketers who served in World War I, World War II, the Korean War, the Vietnam War, Desert Storm, and Desert Shield.
[Nantucket Historic Sites via Visit Historic Nantucket]