When the original Reform School for Juvenile Offenders was built in 1891, its centerpiece was the Administration Building, a Romanesque-style structure called The Castle with an attached chapel, designed by architect Robert Brown Young. This multi-purpose building housed the facility's academic, administrative, and residential functions and reflected the congregate system, which grouped boys together with little regard for age, educational level, physical disability, or mental illness. A 1910 photograph shows the original Castle as a large four-story brick and red sandstone building with a full basement and a clock tower rising eight stories. Its first floor contained the public reception room, school office, a classroom, the dining room, and a sitting room, while the upper floors held additional classrooms, trustees' offices, a library, and dormitories. Other campus buildings included a Girls Department, Power House and Trades Building, Laundry, Buggy House, and Chicken Coop, and the main entrance stood off County Road, later Whittier Boulevard, beside the Whittier Branch of the Southern Pacific Railroad. Reform began in 1912 under Superintendent Fred C. Nelles and continued after his death in 1927, as the school shifted from the congregate system to a progressive system centered more on the individual needs of each child. Between 1915 and 1934, the school was redesigned, facilities were improved and expanded, many old buildings were removed, and a renovated campus embodying Nelles' ideals took shape. During the Nelles era, the school became known for brick and stucco program buildings and Tudor Revival-style residential cottages with English Arts and Crafts influences. An early 1928 aerial photograph shows this shift in the one- and two-story Superintendent's Residence, Administration Building, Auditorium, and Assistant Superintendent's Residence set among agricultural fields and landscaped open spaces. The primary buildings were arranged around a central core reached by two circle drives and surrounded by a park-like landscape, while several new boys' cottages, each housing about 50 boys and named for U.S. presidents, stood in an oval around the Kitchen and Commissary and Infirmary buildings, with well-furnished common rooms, high ceilings, large windows, and wood paneling and floors. These early cottages were later removed during a California Youth Authority building program from 1953 to 1966, when a new modern school with eleven identical dormitory buildings, new program buildings, and detention facilities was constructed. By then, only eight buildings from the Nelles era remained. Among later structures were the Old Maintenance Garage, designed by State Architect W.K. Daniels and completed in 1931; the Gymnasium, built in 1934 in the Romanesque Revival style; the Auditorium, designed by State Architect George McDougall and built in 1923 along the main entrance road; and the Old Infirmary, a Tudor Revival-style hospital completed in 1929 and designed by Deputy Chief W.K. Daniels for the school's medical and dental needs.