Chicago is one of the largest cities in the US, which is clearly apparent from the approach into O'hare International Airport which seems to go on forever. This might make the idea of exploring it daunting, especially if you only have a short amount of time. However, this is where you are lucky, the majority of the iconic landmarks are situated in and around Downtown, which can be done walking, although if you really are short on time then you may wish to jump in a cab occasionally. There is a lot to see, but here are the key things that I would recommend:
1) Architecture Sightseeing Boat Tour I know this sounds 'touristy', however it is a fantastic way to see the city and find out about the history and stories behind some of bold architecture. I would recommend Shoreline Sightseeing. See our Instagram for some of the photos.
2) Navy Pier Especially if it is a beautiful day, this is a really nice place to wander round. It's always buzzing and provides some fantastic views of Lake Michigan
3) Millennium Park Go via 'Cloud Gate' so you get to see the mirrored 'bean'. Be careful as there are often events in the park which restrict access.
4) Riverside Walk This is a fantastic place to wander along, go in the early evening and have a drink at one of the many pop up bars. Also, time it well and you can watch the Centennial fountain spray across the river. This occurs on the hour every hour to celebrate 100 years of reversing the flow of the river, and the clean water.
5) Near North Side
This is a vibrant district a little out of downtown. If you've got an evening spare then head this way for dinner and drinks in one of the many bars. If you're a fan of steak then Gibsons Bar & Steakhouse should not be missed, afterwards you can wander up to E Division St for the nightlife.
6) Chicago Style Pizza
If you're in the Windy City you can't not have a Pizza pie! There are many great options to choose from, I can highly recommend the Lou Malnati's chain, although be careful you're eye's aren't bigger than your stomach.