Quoting from an article in the Atlas Obscura web site:
“This little-known rival to the Library of Congress houses one of the largest collections of pre-1876 American books, newspapers, and manuscripts.
“Plenty of people in Worcester drive by the American Antiquarian Society every day, but few know about the vast amounts of knowledge held inside. This research library and learned society rivals the Library of Congress in terms of its historical content. Historians from all over the United States and beyond make pilgrimages to come here to do their research.”
The full article, along with several pictures of the American Antiquarian Society, may be found at https://www.atlasobscura.com/places/american-antiquarian-society-2. The American Antiquarian Society’s web site may be found at: http://www.americanantiquarian.org.