An American monument, hiding in Somerville

This Prospect Hill monument, built in 1903, commemorates where was the American flag raised for the first time.John Tlumacki/Globe Staff

A quiz: Where was the American flag raised for the first time?

In the unlikely event you guessed the intersection of Munroe and Greenville streets in Somerville, we salute you.

This quiet Prospect Hill neighborhood played a key role in advancing America’s independence from Britain. Hidden in plain sight is the towering, fortress-like Prospect Hill monument, built in 1903, which commemorates this history.

Prospect Hill had a panoramic view of Boston and the harbor, critical for the American forces struggling to hold off British soldiers. When word got out that King George was declaring war on the Colonies, General Washington ordered a new flag of the United Colonies to be created. Up went the Great Union flag on Jan. 1, 1776, with 13 stripes representing the colonies (and, alas, the crosses of Saint George and Saint Andrew in the corner, representing Britain). It’s still flying in this spot today.

The Prospect Hill Monument will be open to the public on Oct. 13, 5-6 p.m.; Oct. 15, noon-2 p.m.; Nov. 3, 4-5:30 p.m.; Nov. 12, noon-2 p.m.

LINDA MATCHAN