The Library of Congress  (http://www.loc.gov/index.html) in Washington D.C. has over 33 million books and 12 million photographs, millions of maps, sheet music, and other manuscripts.

Its holdings make it largest library in the western world; and having been founded in 1800, it is the oldest federal cultural institution in the country.

Source of information:
The World Almanac 2010, original source
The Refdesk 2 Sept 2010, indirect reference source
The Library of Congress (http://www.loc.gov/index.html)

Teaching with the Internet

If you need to use Internet for teaching, "GERSH'S GUIDE FOR EDUCATORS: TEACHING WITH THE INTERNET" created by Dr. Sheila O. Gersh, City College of NY - Center for School Development may be a good site for your reference and here is the link:

http://www.schoollink.org/twin/

In the list, the following are compiled and you can just click your way to some good Internet resources like:
 
CultureQuest, ScienceQuest, Child Safe E-mail

Acrobat Reader Real Audio/Video, Skype

Projects ProjectWorksheets,  Citationmachine

NYS Learning & Teaching, Internet Curriculum ResourcesELEM sites

Sites for young children, Refdesk,  Participating in Projects Virtual Architecture

Post It Add It Conference Presentations For Administrators, CyberGuides video conf. with Japan

Tech Tips (videos),  Interesting Sites, NYS Standards

Literacy Sites, Internet Basics, Subject Matter Links

Science News, Make Your Own Rubrics, Hints for Creating Rubrics WebQuests

WebQuest Resources,  Graphic Organizers

Evaluating Web Sites, ESL Sites , Best WebQuests

Searching on the Internet, Searching strategies, More Searching Tips

Lesson Plans, Project Based Learning

Searching HANDOUT,  Searching with Google Schoolnotes, 
Blackboard Portfolios, Personal Portfolios, Multimedia resources  

Learn to Keyboard

And many more...