The Kemper Building, the world’s tallest marble-clad office building when it opened, remains among the [Chicago’s] tallest skyscrapers. The tower's striking white exterior and strong vertical lines place it squarely within the city’s Modernist tradition. The Kemper Building originally featured a 360-degree public observation deck, including dramatic views of the Chicago River and other nearby buildings—though this attraction was closed within 10 years of opening. This 41st-floor observation deck was reopened for the first time in more than 40 years during Open House Chicago 2012.