Somewhere else I've been working lately is the Bibliothèque Nationale de France, the BNF, at their main Mitterand facility in the 13th district.
It's a huge building designed by Dominique Perrault fitting right into a country that built Versailles, the Champs de Mars, and so on: even though this is a clearly modernist building, its breathtaking scale and rigid geometry owe a lot to the French tradition of gargantuan monumentality.
I joked with a friend about needing to bring some trail mix just to make it from my desk all the way to the washroom. But seriously, except for a few cathedrals and basilicas I don't think I've ever been anywhere with such a pharaonic sense of space. I imagine the endless lengths of steps leading from the sidewalks up to the podium intended for tens of thousands of good citizens to walk up at once, like a scene from a 1920s Russian movie, and the huge ceilings within the reading halls seem fit to fill with millions of volumes in some future millennium when the book-storage towers are full.
Of course, the library's scale is meant to be more impressive than pragmatic, and if I find it a bit overwhelming and pompous, there is something nice about the generosity. The broad podium "deck" overlooking the Seine is a relief in such a dense city, and the tall ceilings in the reading rooms offer plenty of space for the mind to breath that preserves a certain calm even if the rooms are full. It also helps that the quality of finishes is actually pretty good for such a large public complex, with an attractive and simple balance of roughness and refinement (though I find it a tad too grey).
(And for those of you who know of my recent adventure with another research library, the BNF's rules are just as cumbersome, but the staff's attitude at least is far more decent.)