Sears Tower: Visit the Sky deck of the second tallest building in the world for an incomparable view of the city of Chicago. On a clear day you can see four states from the top of the 1,400 foot tall building - Wisconsin, Illinois, Indiana and Michigan.
www.the-skydeck.com/index.html

Museum of Science and Industry: Discover three floors of over 2000 interactive exhibits at the Museum of Science and Industry. You can walk through the middle of a 20 foot tall model of the human heart, explore a real Boeing 727 and make noises in the acoustically perfect Whispering Gallery.
www.msichicago.org

Navy Pier: One of Chicago's most popular landmarks, the pier extends a mile into Lake Michigan and is full of things to do including a 150-foot high Ferris wheel, a six story IMAX theater, shopping, restaurants and an outdoor ice skating rink.
www.navypier.com/

Chicago Art Institute: Many of the most famous pieces of artwork in the world are on display at the Chicago Art Institute. See the world-renowned American Gothic by Grant Wood as well as paintings by Monet, Renoir, Gauguin and van Gogh.
www.artic.edu/aic/

Field Museum: The Field Museum houses thousands of natural history exhibits. While you are here, don't miss Sue, the world's largest T. Rex dinosaur or the Underground Adventure simulation, a "total immersion environment" populated by giant robotic earwigs, centipedes, wolf spiders, and other subterranean critters.
www.fmnh.org