Millennium Park is 24.5 acres and right downtown (on Michigan between Randolph and Monroe Streets) on land previously owned by the Illinois Central Railroad. World-class music, art, architecture and gardens merge here. On warm, sunny days, kids soak in an interactive fountain designed by Barcelona artist Jaume Plensa, which features two 50-foot-high glass block towers and a reflecting pool. Another sculpture, Cloud Gate by British artist Anish Kapoor, draws crowds who come to look at the elliptical reflection of the skyline in the jellybean-shaped sculpture's polished stainless steel (it's gained the nickname "the Bean"). In winter there's ice skating, while warmer weather brings free concerts at the Jay Pritzker Pavilion, designed by Frank Gehry.
There are many tours of Chicago's must-see architectural sights, but our favorites are those offered by the Chicago Architecture Foundation. There are guided tours by bus and on foot, but our favorites are the boat tours on the Chicago River (offered from spring through fall) for a unique perspective on structures like the 90-acre Merchandise Mart. You can go the self-guided route by purchasing a detailed map at the CAF's headquarters in the historic Railway Exchange Building, where you'll also find an excellent gift shop.
Families and nature lovers won't want to miss a visit to the Shedd Aquarium. Permanent exhibits at the Shedd include the kid-friendly Polar Play Zone (don't miss the penguins!) and the Wild Reef, where floor-to-ceiling windows let you view sharks, stingrays, eels and more. Be warned that the line to get in can stretch out the door and down the steps; get there when it opens to try to beat the crowds.
Got kids in tow, or feel like acting like a kid yourself? Don't miss a visit to the lakefront Navy Pier, a 1916 landmark that's been reborn as a venue of shops, restaurants, gardens and entertainment attractions -- including a 196-foot Ferris wheel and an IMAX theater. The Pier is also home to the Chicago Shakespeare Theater and the Chicago Children's Museum, where the mostly hands-on attractions include a Climbing Schooner kids can explore. Boat tours of Lake Michigan are offered from spring through fall.
Dinosaur fans shouldn't miss a stop at the Field Museum, home of Sue -- the largest, most complete and best preserved Tyrannosaurus rex fossil ever discovered. The Field also boasts mummies, Egyptian tombs, a Maori meeting house, and millions of examples of anthropology, botany, geology and zoology.
A favorite place for visitors to pose for vacation photos is with the lion sculptures guarding the front steps of the Art Institute of Chicago. Once you get past the beasts, you'll find in the massive Beaux-Arts building one of the top art collections in the world with works from 3000 B.C. to the present. A highlight is the Impressionist and Post-Impressionist collection with works by Monet, Renoir, Degas, Van Gogh, Gauguin, Seurat and others. The Art Institute was expanded in May 2009 with a glass, steel and limestone wing designed by architect Renzo Piano.
The coolest thing about the Lincoln Park Zoo is that it's one of the few remaining zoos that's still free. Open every day of the year, the zoo is home to hundreds of mammals, reptiles and birds, and is a nice place for a stroll, not far from downtown.
The National Museum of Mexican Art, located in the lively Pilsen neighborhood, has one of the nation's largest collections of Mexican paintings, sculptures, prints, folk art, textiles and photography.
Oak Park lays claim to not one but two of Chicago's famous 20th-century figures. You can tour architect Frank Lloyd Wright's home and studio, and see several examples of his famous Prairie School style, in this leafy residential neighborhood. Just a few blocks away is the birth home of Ernest Hemingway. Don't miss a stop in the small Ernest Hemingway Museum to learn about the literary giant's life and loves.
Baseball fans should take in a game at the legendary Wrigley Field, built in 1914. (It's the second oldest ballpark in the country, behind Boston's Fenway.) Can't get tickets to a game? Take a stadium tour for a look behind the scenes.
About 25 miles west of Chicago, the 1,700-acre Morton Arboretum is one of the state's most popular public gardens. The arboretum's walking trails take you past highlights such as the towering Millennium Oak (it's more than 250 years old), the flower-filled Schulenberg Prairie and the Maze Garden (if you're not up for navigating the labyrinth yourself, you can climb to a lookout platform and watch other visitors fumble their way through the maze).