Visitors (meaning tourists) can't go inside the reading room, located in the Thomas Jefferson building, but are allowed to view and photograph it from an inconveniently glassed in gallery above (the glass is OK, but there are panels of it in odd places that I had to crop out). It used to be that you could go inside the reading room, which we did years ago, then you had to go on a tour to even view it, and now you can just go up the stairs and look.

What you see is this dome: