What would a public library be at three in the morning?

Dear Marrow & Vane, Our branches close at eight. Night returns come through the slot until morning, and nobody sees them. We want people to keep thinking of the library after dark, but we cannot staff it and we cannot open it. The shelves are dark, the windows are dark, and the building looks closed because it is. Every night a few hundred books come back while the city is still awake. What would a library be at three in the morning? The Head of Service, Kellsmoor Public Libraries