America's highest glass observation deck cracks under foot, shocking holidaymakers.The Willis Tower's glass Skydeck is a favourite destination for thrill-seekers in Chicago, but tourists standing on the glass-bottomed observation... " />

Willis Tower horror at 412m as Chicago SkyDeck cracks underfoot

America’s highest glass observation deck cracks under foot, shocking holidaymakers.The Willis Tower’s glass Skydeck is a favourite destination for thrill-seekers in Chicago, but tourists standing on the glass-bottomed observation…