What to do with that space between the book shelf and the ceiling in the library?

In my local library, they use the excess space for posters, projects, and books (not for sale but for show), just to tell the new comers just how devoted you really are. If I had to say anything, I would suggest section labels if not already labeled, but it really depends how big, how popular, and how organized this library really is. I hope this helped.

He developed the concept of linear perspective, and he had the ability to solve architectural problems using mathematics.