Willis Tower, located in Chicago, has a unique aspect to its architecture, intended to draw in tourist and sight-seekers.  Four sky deck ledges extend a little more than four feet from the edge of the building.  The boxes are located directly off the one hundred and third floor of the Willis Tower and are made completely of glass, allowing visitors to see the street nearly one thousand and four hundred feet below them.  The glass walls enable tourist to see fifty miles into the distance, across four states.  Despite the material at hand and the corresponding inclination to feel a lack of solidity at walking on apparently nothing, the ledges are said to have a capacity for holding five tons.

Since their implementation in 2009, over six million people have come to the ledges to experience the feeling of walking on air.  With each box constructed using three separate layers of one-half inch glass and a protective coating, there has never been an issue.

Shot of Willis Tower, featured on Ivana De Domenico's travel blog

Behold, the Tower Willis (née Sears)

However, according to an article completed by CNN Travel, the experience was not a relaxing endeavor for one family.  Alejandro Garibay and four of his family members were enjoying the sights when they suddenly heard the distinct noise of glass cracking.  Small cracks started to form in the actual glass, prompting Garibay and his family to quickly jump from the box.  By the end of the evening, the glass appeared to be utterly shattered.

Shortly after the incident, Bill Utter, a Willis Tower spokesman, clarified that the box itself was not what cracked, despite appearances.  The protective coating around the glass had cracked, meaning the integrity of the sightseeing box was never compromised and none of its occupants were ever in danger.  According to Utter, the cracking of the protective coating is a somewhat common occurrence and, fundamentally, is the purpose of having the protective coating to begin with.  Within a few short days, administrators with the Willis Tower updated the building’s Facebook page to indicate that the protective coating had been replaced and the box was once again open for business.