Daredevil Nik Wallenda begins his tightrope walk uphill at a 15-degree angle from the Marina City west tower across the Chicago River to the top of the Leo Burnett Building. (AP Photo/Paul Beaty)
Daredevil Nik Wallenda finishes his tightrope walk uphill at a 15-degree angle, from the Marina City west tower across the Chicago River to the top of the Leo Burnett Building. (AP Photo/Charles Rex Arbogast)
The shadow of daredevil Nik Wallenda is cast against the West Marina Tower as he begins his tightrope walk uphill at a 15-degree angle. (AP Photo/Charles Rex Arbogast)
Daredevil Nik Wallenda, left center in red, makes his tightrope walk uphill at a 15-degree angle. (AP Photo/Charles Rex Arbogast)
Crowds begin to gather on Chicago's W. Wacker Dr. before daredevil Nik Wallenda begins his tightrope walk. (AP Photo/Charles Rex Arbogast)
Daredevil Nik Wallenda, steps out on the wire backwards, for a live television show before his tightrope walk uphill at a 15-degree angle. (AP Photo/Charles Rex Arbogast)