It is the longest indoor stair ascent in the world at two thousand 109 stairs.
Two thousand people spent their Sunday catching the view from atop the Sears Tower but they got there the hard way.
The line formed early for the "go vertical Chicago" climb this morning.
Participants went from the lobby to the 103rd floor sky deck observatory one step at a time.
Organizers claim it is the longest indoor stair ascent in the world at two thousand 109 stairs.
The event raised money for the Damon Runyon Cancer Research Foundation.