Constructed between 1867 and 1872, the U.S. Custom House combines Second Empire and Renaissance Revival styles. The Customs House was built after the Great Fire of July 4, 1866. The fire destroyed Portland's Exchange Building, which had housed the customs office, post office and courts. Another 1,800 buildings in the city center were also destroyed. The Custom House is typical of the notable designs completed under the direction of Alfred B. Mullett, Supervising Architect of the U.S. Treasury from 1865 to 1874. The Custom House is the best of Mullett's work in Maine and continues to serve its original function. It is listed in the National Register of Historic Places.