875 N. Michigan Avenue (formerly the John Hancock Center) and 360 Chicago

Designed by Skidmore, Owings & Merrill, this multipurpose skyscraper is distinguished by its tapering shape and enormous X braces, which help stabilize its 100 stories. Soon after it went up in 1970, it earned the nickname "Big John." No wonder: it's 1,127 feet tall (the taller east tower is 1,506 feet counting its antennae). Packed with retail space, parking, offices, a restaurant, and residences, it has been likened to a city within a city. Like the Willis Tower, which was designed by the same architectural team, this skyscraper offers views of four states on clear days. To see them, ascend to the 94th-floor observatory—now dubbed 360 Chicago ($30). While there, visitors can grab a cocktail, beer, wine, hot drink or nonalcoholic beverage at Bar 94, which can only be accessed with a General Admission ticket. Thrill seekers can pay an additional fee to take advantage of the tower's most exciting feature, The Tilt ($8), which has eight windows that tilt downward to a 30-degree angle, giving you a unique perspective on the city below. Those with vertigo might prefer a seat in the bar of the 96th-floor Signature Lounge; the tab will be steep, but you don't pay the observatory fee and you'll be steady on your feet.