Prospect Hill is easily the most historically significant location in Somerville. The battle of Concord-a prolonged fight consisting of pursuits, skirmishes, and tactical withdrawals through Middlesex County-actually ended at the foot of the hill. The retreating Continental Army also made a defiant stand on Prospect Hill against pursuing British troops. Prospect was one of three hills fortified for the Continental siege of British-occupied Boston in 1774. However, Prospect Hill's chief claim to fame is that there, on January 1, 1776, the first flag of the United Colonies was raised on General Washington's orders.

The tower and park on Prospect Hill are such Somerville icons it is difficult to believe that they would not exist now were it not for the efforts of concerned citizens at the end of the nineteenth century. After the War of Independence, Prospect Hill was farmed as it had been before the war. During the post-Civil War industrialization of Somerville, cheap housing for workers was built on part of Prospect Hill. Much of the rest of the Hill was dug up and used to fill in Miller's River. During the 1870s a group of Somerville businessmen proposed building a hotel on the Hill. Fortunately, a number of civic groups began to lobby for the purchase of the remainder of the hill and its preservation as a park. In 1896 momentum for preservation accelerated with the formation of the Prospect Hill Park Association. In 1898 the city government officially decided to the purchase the Hill for preservation. At left is the design for the park proposed by City Engineer Ernest Bailey. The park was completed and officially dedicated (with a somewhat more imposing-looking tower) in 1903.