Jumping back to New York, but staying with the revolution theme, this little monument within a circle certainly looks peaceful enough but it has had a contentious history. The monument is to British Major John Andre, who plotted with Benedict Arnold to turn West Point over to the British. Those plans went awry and Andre was soon caught in Tarrytown. He was then brought across the Hudson to Washington's headquarters in Tappan. Andre was tried and convicted in the '76 House tavern (still open after 230 years!). The monument, is maybe a half-mile away from the center of Tappan and is where Andre was hung and buried.
Andre's remains were returned to England in 1821. In 1879, Cyrus Field, who laid the first trans-Atlantic telegraph cable, paid for this monument. Despite being a century after the revolution, the monument was controversial and was vandalized and blown up. Field replaced the original monument with the current one and surrounded the new monument with the iron fence. Someone tried again to blow it up in 1885, but it's been pretty peaceful since then. After Field died his heirs refused to pay the property tax on the small plot of land and Rockland County, which could not find a buyer, took possession.
The tacky brass plaque commemorating "the fortitude of Washington and his generals" was attached to the monument by the American Scenic and Historic Preservation Society in 1905.
If you're really motivated and read the pages I've linked to you'll notice some confusion about the ownership of the land. Rockland County says they took possession from the ASHPS in 1983. Other sources say the county got the land in 1904. If it weren't past my bedtime I'd investigate further.