The Collegiate Gothic style of Abele Quad is carved out of “Duke Stone,” a special stone from a quarry in nearby Hillsborough. The proximity of the quarry and versatility of the rock has made this an essential and valued building material for Duke. Duke’s “stone era” was first interrupted by the construction of the College of Engineering—now Hudson Hall—and the Physics Building following World War II; each was built of less expensive red brick in a Georgian style. Duke returned to stone with the completion of the Classroom and Administration Building—now the Allen Building—in 1954. Since then, buildings at Duke have varied in style and primary building materials, but have retained accents of the characteristic stone.