There's Thomas Jefferson's original rough draft of the Declaration of Independence, which shows his literary flair and key changes made by Benjamin Franklin, John Adams and the Continental Congress.
There's a copy of the Gutenberg Bible, the first great book printed in Western Europe from movable metal type. And there's the only surviving copy of Martin Waldseemuller's 1507 map of the New World, the first to identify the American continent.
If you've never seen the remarkable documents or visited the National Library of Congress, there's an opportunity to sample its collections today in Monument Square. The library's free mobile exhibit, "Gateway to Knowledge," will be open from noon to 8 p.m.
"It's very impressive," said Tom Kelley, a college student in Portland who visited the exhibit on Friday. "I've never been to the Library of Congress, but I think I'll have to go, after seeing this."
The exhibit is presented in a custom-built, 18-wheel truck that contains several interactive, multimedia displays. They feature copies of priceless documents highlighting various collections from the nation's oldest federal cultural institution, which started with more than 6,000 books from Jefferson's personal library.
Portland is the exhibit's 84th stop on a nationwide tour that started a year ago. The exhibit will return to Washington, D.C., later this month for its 90th and final stop, during the National Book Festival on Sept. 25-26. This stop is hosted by Portland's Downtown District and the Portland Public Library.
The Library of Congress contains 145 million items, including books, maps, movies, music, comic strips and digital items, according to one display in the exhibit. They are written in 470 languages and are stored on 745 miles of bookshelves. The library receives 22,000 new items each workday and adds about 10,000 of those items to its collections.
The exhibit often impresses people who see it, said Abigail Van Gelder, a docent on the tour.
"People are surprised about what's available at the library or how much access they have," Van Gelder said. "There are very few restrictions. Many items are on display, and there are new exhibits all the time. Most items can be viewed with permission if people have a specific reason, such as research."
The exhibit in Monument Square attracted Elaine and Peter Connolly of Hartford, Conn., who are on vacation.
"It's so interesting," Elaine Connolly said, standing before a display about Clara Barton, founder of the American Red Cross. "These are treasures that we should remind ourselves that we have."