U.S. architect, significant for the forceful originality of his buildings and for his influence on Louis H. Sullivan (Sullivan, Louis), who was a draftsman in 1873 for the Philadelphia firm of Furness and Hewitt (later Furness, Evans, & Company).

The work of Furness, who was familiar with the architectural ideas of Ruskin and Viollet-le-Duc, is largely in the Romantic Revival tradition of the Neo-Gothic. His highly personal style is expressed in his polychromatic decoration and his massive geometric ornamentation, the shapes of which were frequently abstractions of forms found in nature. They contributed much to the development of Sullivan's theories of organic architecture and ornamentation. Furness' major works include the Pennsylvania Academy of the Fine Arts (1872–76), the Provident Life and Trust Company Bank (1878–79; demolished), and an addition (1892–94) to the Broad Street Station of the Pennsylvania Railroad. Besides his Philadelphia works, Furness designed buildings throughout Pennsylvania and also in Delaware and Maryland.