The Chicago Tribune recently asked locals and tourists alike for directions to the Willis Tower. Most couldn't pick it out on a map. Even cab drivers had never heard of the building. That's because last Thursday, the Sears Tower officially changed its name to the Willis Tower.

The 110-story Sears Tower opened in 1973 in Chicago's West Loop and was named for its original occupant, Sears Roebuck & Co., which has since moved its headquarters to the Chicago suburbs. The building now bears the name of the London-based insurance firm, Willis Group Holding, which owns the naming rights for the next 15 years. At 1,450 feet, it’s still the tallest building in North America, but is now dwarfed by Taipei 101 in Taiwan, the Shanghai World Financial Center in China and the Petronas Towers in Kuala Lampur, Malaysia.

At last weekend's Pitchfork Music Festival in Chicago's Union Park the name-change cropped up during in-between song banter from several bands. Brooklyn's Yeasayer poked fun at the "Bruce Willis” Tower, while an audience member pointed out how beautiful the Diff'rent Strokes-inspired "Whatchoo Talkin' About Willis" Tower looked shimmering in the midsummer sunset.

This isn't the only Chicago landmark that has been stripped of its iconic name though. In late 2006, the Marshall Field's department store was converted into a Macy's. And just as locals still call it Marshall Field's, many refuse to call the obsidian skyscraper anything but the Sears Tower.

Lyndsey Matthews is a freelance editor at Travel + Leisure.