One of the most remarkable architectural elements of the indoor schools lies in their roofing framework, which significantly changed during the period. The Delorme, Polonceau or the Emy roofing frameworks illustrate the development of the size of rides indoor schools as well as the industrial techniques available to builders. The wide roofing framework (opposite) of the indoor school in the Rochambeau district is an example of Polonceau roof invented in 1837, combining wood, iron and cast iron. This is the only example of its kind in good condition kept in the Centre region.