Cornelius Coolidge (1778–1843) was a real estate developer in early 19th-century Boston, Massachusetts, who constructed buildings in Boston's Beacon Hill neighborhood, and elsewhere. As a young man he had been involved in maritime trade, and not always within the prescribed laws. During the War of 1812, the brig Dispatch owned by Coolidge and Francis Oliver was captured outside Boston Harbor by the Salem privateer Castigator on suspicion of having been trading with the enemy. Coolidge and Oliver manned two boats with 45 armed men, rowed down the harbor, and regained their brig after an exchange of gunfire. However, the brig was restored to the privateers by the district court.
Described variously as an architect, housewright, builder, designer, and real estate broker, Harvard-educated Coolidge brought many buildings into being. Clients of Coolidge & Co. included some of Boston's more prominent residents, such as David Sears and Charles Francis Adams. He conducted business with John Hubbard, Joseph Morton (brother of Perez Morton) and others. He was also a proprietor of the Boston Mill Corporation.
Around 1825, Coolidge and Nathaniel Amory began developing property in Nahant, Massachusetts, for construction of summer homes. The first homes sold in 1827. Clients included David Sears and others. On Beacon Hill, Coolidge built houses on Chestnut, Mount Vernon, Acorn, Joy and Beacon Streets, including Louisburg Square. Several remain in existence, including:
- 33 Beacon Street (George Parkman house), 1825.
- 50 Chestnut Street (Francis Parkman house), 1830s.
Coolidge led an active social life. He was one of the first subscribers the Boston Athenaeum. He attended the gala opening dinner party for the newly built Tremont House hotel on October 16, 1829, along with mayor Josiah Quincy, Daniel Webster, Edward Everett, Harrison Gray Otis, and others.
- Stephen Clark (USP Castigator) v. Dispatch. War of 1812 Prize Case Files 1812-1815, Waltham, Mass.: National Archives and Records Administration
- Diary of Charles Francis Adams, Harvard University Press, 1986
- Historic American Buildings Survey, Library of Congress
- Sarah Wentworth Apthorp Morton, 1759-1846, Dorchester Atheneum
- "Boston Mill Corp. certificate".
- Rebecca M. Rogers (1974), "Resort architecture at Nahant, 1815-1850", Old-Time New England
- Allen Chamberlain (1925), Beacon Hill, Its Ancient Pastures and Early Mansions, Boston: Houghton Miffin Co.
- Susan Southworth (2008), AIA guide to Boston, Guilford, Conn: Globe Pequot
- "Our Flag over the Common", Northeastern Alumni Magazine
- Josiah Quincy (1851), The history of the Boston Athenæum, Metcalf and Company
- "The first lithograph menu ever used; Dinner in the New Tremont House, Oct 16, 1829, Marked Opening of the High-Class Hotel in America", Boston Daily Globe, December 20, 1914
- "Original Bank Circular, 1809", Proceedings of the Massachusetts Historical Society 11, 1870: 306–308
- Andrew Preston Peabody. A sermon preached in commemoration of the founders of the Nahant Church: at the dedication of a tablet erected to their memory, July 22, 1877. Press of John Wilson and Son, 1877.
- Allen Bernstein (October 1948), "Cornelius Coolidge, architect of Beacon Hill row houses, 1810-1840", Old-Time New England 39