Rogers and Captain Forbes collaborated on the design, which included nautical elements. Its interior retains many original features, including an elliptical staircase (resembling those of lighthouses) rising through three stories, leading to a cupola to view ships arriving at Boston Harbor. It has walls thick, which were originally sheathed with shiplap siding. A partial upper floor was originally illuminated by porthole windows; this was altered in the 1880s, when the roof was raised and sash windows were installed. The interior has been little altered, primarily by the addition of 20th-century conveniences, including plumbing and electricity. Interior additions (1872) include tiled fireplace surrounds in the High Victorian Gothic style.