While you do have to be registered with the Library to go into the reading room, the tour guide will show you around the atrium area and point out interesting aspects of the building and reading room. The guides were very informative and explained artistic touches, and architectural meaning that I would never have even noticed. What looks like an overly ornate area, has real meaning all around that I would never have seen. I was so surprised that we had a treasure like this building in the US, and even more so that I didn't know anything about it! I had expected to be going to see piles of books. (yawn) but no, the architectural tour was entertaining and great! Also. the bookstore is great, you'll want to buy everything!