When creating his first library, the Biblithèque Sainte-Genevieve, Labrouste set forth his design for what a modern library situated in the heart of Paris should look like. The structure was outfitted with the newest of technological advances, large windows for natural light, a below floor heating system to keep the legs of studiers warm, and the use of cast iron arches. These components were also included in his later Bibliothèque Nationale, in which he melded the classical nature of a city like Paris with the newest of the modern world. In the main reading room, he has included his trademark cast iron, alongside a caryatid entrance, roundels depicting classic intellectuals, and large glass oculi at the top of each of his nine domes.