Plymouth's Training Green is one of the oldest continuously used parks in the country. This ornamental park was designated as “a perpetual common or training place” in 1711, when the town designated it as the official Training Green, and it remained a muster field into the 19th century.

The local militia trained here for many years. The design for the walks and perimeter curbing was done in 1889 by the well-known landscape architect, Frederick Law Olmstead. The Civil War Monument, erected in 1869 is dedicated to the soldiers and sailors of Plymouth who lost their lives in both the Civil War and the War of 1812.