Dorchester Heights is the peninsula shown just below center on this 1775 map

CREDIT: Page, Thomas Hyde, Sir. “Boston, its environs and harbour, with the rebels works raised against that town in 1775, from the observations of Lieut. Page of His Majesty's Corps of Engineers, and from those of other gentlemen.,” 1775(?). Geography and Maps Division, Library of Congress. Call Number G3764.B6S3 1775 .P3 Faden 34.