The Bibliothèque Nationale has 3×3 grid of domes with an oculi in the center allowing for light to fall down. There may have been a deeper meaning, having wisdom pour down into the library, falls in line the the Ionic order capitals. There are vaulted ceilings which are no longer made of stone but instead by reinforced plaster and there is iron openwork throughout. It is also modernized with the use of steel and iron in the columns instead of marble or stone. The columns are also very thin in proportion which challenges the principal orders that were more bulky. There are also large yet delicate actuated windows, helping to make the floor space feel larger.