Chicago is really a nice discovery, starting from its airport, which welcomes travelers to the sound of music, multicolored installations and sound works of art. In addition to this it is very well connected to the city, just take the metro (CTA Trains, blue line, direction Forest Park) to easily reach downtown with a ride of just half an hour.
Upon arrival at the airport or at any metro station I recommend buying a CTA Pass of the duration of your stay as it guarantees you unlimited rides on the metro and CTA buses, especially useful in the evening after walking all day, your feet will thank you. The best thing to do as a first approach to the city is undoubtedly get lost in loop, city center, to discover its tall skyscrapers, its street art (do not miss the installations by Picasso and Mirò), the Chicago Theater, the home of the Chicago Tribune and take a long walk Michigan Avenue and the River Walk (very romantic in the evening).
Only after familiarizing yourself with the center, head towards the Navy Pier, the port, to board a 'Architecture River and Lake Cruise, the cruise along the river that will make you discover the center from a completely different perspective, accompanied by the curiosities listed by the guide, and that ends in style with a breathtaking ride on the lake, admiring the splendid skyline of the city.
Returning to the Loop, take the time to explore Millenium Park, a perfect combination of art and nature, which houses the towers of the fun Crowd Fountain, the pavilion designed by Frank Gehry, Cloud Gate, also called "the bean" and the sinuous Pedestrian Bridge, also redesigned by Frank Ghery.
In the immediate vicinity it is also worth visiting The Art Institute of Chicago and Buckingham Fountain, on the shores of Lake Michigan. To round off, spend half a day at Lincoln Park and visit its free zoo and Lincoln Park Conservatory. The more daring will not miss a visit to the Willis tower, where on the 103rd floor you can experience the thrill of literally having the city at your feet: the four transparent terraces guarantee abreathtaking experience that is not easily forgotten.
Not to be missed: the lights of the skyscrapers reflected in the evening Cloud Gate, the skyline at sunset as seen from Buckingham Fountain and the Architecture River and Lake Cruise.