When met with strong winds, Chicago's skyscrapers sway back and forth ever so slightly. If you're looking for proof, check out the audio clip above taken from an apartment in the John Hancock Center during a storm in April. The loud, unsettling creaking is enough to scare the bejesus out of anyone who forgot about the existence of engineers.
The Hancock seems particularly prone to swaying. The city's fourth-tallest building sits along the windy lakefront and its north-south side is more than 150 percent wider than its east-west side.
If you hear this creaking in a building on a windy night and become uneasy, just pretend that the noise is coming from the ghosts in Poltergeist III. That will make you feel better.