Willis Tower
In June 2006, seven men were arrested by the FBI and charged with plans to destroy the tower. The case went to court in October 2007. After three trials, five of the suspects were convicted and two acquitted. The leader of the group, Narseal Batiste, was sentenced to 13.5 years in prison. In response to the possible threat of an attack, the building's largest company space at this time, Ernst & Young, moved to North Wacker Drive in early 2009.