CHICAGO -- Yesterday, while on a day trip in Chicago, my family and I squeezed into a packed elevator and rode 103 floors -- that's 1,353 feet -- to the top of the Sears Tower, 233 S. Wacker Dr.

I didn't feel a single flutter of anxiety until I saw the new glass boxes that hang from the tower's facade and allow visitors to "step off the ledge." The glass boxes -- which opened to the public on Thursday, July 2 -- jut out 4 1/2 feet from the tower and are completely transparent, supported by steel beams.

It's an extremely freaky feeling to step into one of the boxes and see exactly what it looks like to free fall from a quarter-mile in the sky. The panoramic view is both terrifying and breathtaking, and I'm not even afraid of heights.

I did not see a single sign stating a weight limit -- or person limit -- for the boxes, and I found it slightly unnerving that visitors were piling into them like they did the elevator. (Later, I learned that each box can hold at least five tons.)

My kids were super eager to test them out, and I admit I may have directed them towards a box that appeared to have lighter people on board. I know this makes little sense considering that each box could hold an elephant, but the high altitude might have enhanced my irrational mom fears.

One woman stepped into a box and stepped right back out. "I can't do it," she said to me with wild, wide eyes. My sons, however, jumped up and down (!) from inside the box and yelled out, "Whoa! This is cool!"

I stood in one of the glass spaces for about a minute. I felt like Wile E. Coyote from the old Road Runner cartoons when he ran off the edge of a cliff and always froze in mid-air for a second or two, sometimes just to open an umbrella, before plunging to the ground.

Then I thought, "I think I see my dad," which is what Cameron said in the 1986 comedy "Ferris Bueller's Day Off" when he looked down from the top floor of the Sears Tower.

Finally, I thought about glass, and how, in my lifetime, I have seen it crack, smash, explode and shatter. And that's exactly when I stepped out of the box.