The docent tour is a must to see the main chamber of the library, but if you are unlucky there are restorations blocking the view. The architecture is incredible and almost over the top. (The cherub with a phone is a blast.) The exhibits are surprisingly interesting and the Jefferson library is really nice. The tour is short, but you can spend a lot of time browsing the exhibits. Not too badly crowded either, so it is probably the calmest and most relaxing attraction you can take in D.C.
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