The King Caesar House is a historic house located at 120 King Caesar Road, Duxbury, Massachusetts. It is operated as a non-profit museum by the Duxbury Rural and Historical Society. The Federal style house, completed in 1809, was built for Ezra Weston II (1772–1842) and his wife, Jerusha Bradford Weston (1770–1833). Like his father, Weston was known as "King Caesar" for his success in shipbuilding and shipping. During the 1830s and 1840s, the firm of E. Weston & Sons ran the largest mercantile operation on the South Shore of Massachusetts. In 1841, U.S. Senator Daniel Webster, during a speech in Saratoga, New York, made the claim that Weston was, "the largest ship owner, probably, in the United States."