The firm specialized in churches, hotels and palatial residences, especially crenelated mansions, such as Maybrook (1881), Druim Moir (1885–86) and Boldt Castle (1900–04).
The younger men formed their own firm, Furness & Hewitt, whose most notable building was the Pennsylvania Academy of the Fine Arts (1871–76).
Every feature in his clean cut, rather elongated face, bespoke intelligence and kindness, in fact a big heart.
Furness & Hewitt continued until 1875, and George opened his own firm, making his brother William a partner in 1878.
In the early 1880s, Henry H. Houston, a director of the Pennsylvania Railroad, began developing 3,000 acres (12 km2) in the western Chestnut Hill section of Philadelphia.
The Hewitt brothers did the planning for the upper-class suburb and designed the principal buildings, including a resort hotel, the Wissahickon Inn (1883–84) (now Springside Chestnut Hill Academy); the first clubhouse for the Philadelphia Cricket Club (1883–84, burned 1909); Houston's own mansion, Druim Moir (1886); and St. Martin-in-the-Fields Episcopal Church (1888).