The White House....for kids. Learn about our presidents. There's even information about their pets! http://www.whitehouse.gov/kids/whlife/index.html
National Geographic for Kids http://www.nationalgeographic.com/kids/
Map Puzzles for places all over the world! Great to practice state/country locations as well as state capitals. Lots of fun too! http://www.yourchildlearns.com/map-puzzles.htm
Washington DC info http://kids.dc.gov/kids_main_content.html
Liberty Bell http://www.enchantedlearning.com/history/us/monuments/libertybell/