The marble blocks on the exterior of the building help protect the collection from sunlight and also help regulate the temperature and humidity inside.

Since Morgan was in her chair and the exhibitions were on the second floor, we got to use the elevator inside this center section (we walked through a large section of dictionaries to get from the elevator back outside). Our security escort told us that the books in this visible section is only a very small percentage of all of the books in Yale's collection.

Gutenberg Bible