Southern view from John Hancock Center, Chicago USA

The observation deck of the top of the John Hancock Building offers such an amazing view over the city in 360 degrees. The 2 best views are towards the city, which is shown in this image, and the view down the beach at sunset.
Tripods are usually not allowed, but you can use the heater on the floor to stabilize your camera. Mondays seem to be the exception though, so you should ask if you are allowed to use a tripod on this day.

The John Hancock Center is pretty easy to find as one of the highest buildings in Chicago. The best way to get there is probably by subway. The admission currently costs about 22$ and you can enter this building from 9am until 11pm.

Insider trick: If you don't want to pay the admission you can also get up there to a restaurant, which is just below the observation deck. Entrance is free, but if you want to take pictures, the observation deck seems to be the better alternative.