Labrouste’s architectural design included both classical and modern elements. In its classical aspect, ribbed vaulting is reused again with ionic capitals, which represents wisdom and corresponds to the spirit of a library. Moreover, Instead of using stones, cast iron was used in pillars and roof framing. The use of cast iron shows its modern aspect and also makes the architecture light. The use of cast iron makes the pillars extremely thin, thus increasing the interior space and lighting of the library.