GO SEE Millennium Park! It's in the heart of downtown Chicago and one of the MAJOR tourist attractions. There you'll see the famous Cloud Gate sculpture, which looks like a huge chrome bean. You also experience the cool interactive Crown Fountain, which is my personal favorite. If you arrive at the park first stop at the welcome center located at 201 E. Randolph Street in the Northwest Exelon Pavilion. There you'll find friendly guides that will help you plan your visit.
Things to do
The Art Institute of Chicago is a major prestigious destination you must add on your list of places to visit in Chicago. The lion guarded building houses 300,000 works of art and is also a school. The general hours are: Monday–Wednesday 10:30–5:00, Thursday 10:30–8:00 Friday 10:30–5:00, Saturday–Sunday 10:00–5:00. Check out the site for info on current exhibitions and events.
It is currently the fourth-tallest building in Chicago and the sixth-tallest in the United States. I recommend to have a beer or something else in "The Signature Room" on the 95th Floor. The views are reallly amazing, even more at night.
Even if it looks like a touristic thing it's worth it!! The views from the river are great!
It's the best place to see Chicago architecture :)
There are lots of them. Take the one from the Chicago Architecture Fopundation and at least you for sure that they are going to give you the best info.
It's 28$ per person and the duration is 90 minutes
Do not miss this neighborhood, the coolest of Chicago!
The subway would leave you in what they call the "six corners", a place where there are 6 buildings (hence its name:).
Any of the streets coming out of this place is full of vintage shops, record, small restaurants, bars, live music places ....
Any day of the week there is a lot going on and you can go out at night until late. Take your time, because there is much to do in this area:)

