C.B.J. Snyder was an architect and mechanical engineer who served as Superintendent of School Buildings for the New York City Board of Education between 1891 and 1923. During his tenure he was responsible for the design and construction of more than 350 elementary, middle, and high schools in the five boroughs. Snyder is know for innovating the design and construction process. The resulting schools have been praised for their high quality, longevity, and architectural beauty. Snyder worked in a number of styles, favoring Beaux Arts, English Collegiate Gothic, and Renaissance Revival. Another feature of his buildings were their mid-block location, preferring to keep these places of education away from the busy, noisy, and (perceived) pollution of the avenues. He believed that schools were civic monuments that were necessary for a better society and he focused on health and safety issues, improving the fire protection, ventilation, lighting, and classroom size.

Public School 31, April 30, 1941. Affectionately called the "Castle on the Concourse," Public School 31 was a Collegiate Gothic style school designed by C.B.J. Snyder and completed in 1899. The design is notable as one of Snyder's first forays in late Gothic features such as pointed windows topped with stone tracery. The irregularity and deeply pointed gables gave the building its castle-like look and created an eye-catching visual on the broad Grand Concourse. The school was designated a landmark in 1986 but closed in 1997 amid concerns of structure deterioration. For the next 15 years the city allowed the building to continue its deterioration. In 2014 the city requested permission from the Landmarks Commission to demolish the building. Despite disgust at the situation and virulent opposition by the local community and preservationists, the building was finally razed in 2015. A large number of architecture features of the 19th century school were saved during the process of demolition and are required to be included in the design of whatever new structure rises in its place.