The house proper was completed in 1798, with a Mr. Jones of Northumberland employed acting as master carpenter. Built in an 18th-century Georgian style, the "balance and symmetry" of the architecture signaled "subdued elegance". The house was accented with Federalist highlights, such as "the fanlights over the doors and the balustrades on the rooftop belvedere and main staircase", marking it as distinctly American. Douglas R. McMinn, in the National Register of Historic Places nomination for the Northumberland Historic District, calls it a "mansion" that is "probably the finest example of the Federal style in the region". As William N. Richardson, the site administrator for the Joseph Priestley House in the 1990s, notes, Priestley's American home did not resemble his "high-style Georgian town house" that was destroyed in Birmingham; rather, it was "plain" and built in the "American vernacular".