Not content with having the tallest building in America , the owners of Sears Tower in Chicago have installed four glass box viewing platforms which stick out of the building 103 floors up. The balconies are suspended 1,353 feet in the air and just out four feet from the building's Skydeck.
Floating on air: Visitors get their first view from The Ledge, four glass balconies suspended from the 103rd floor of Chicago 'S Sears Tower .
 
Designers  say the platforms - collectively dubbed The Ledge - have been purposely designed  to make visitors feel as they are floating above the city.   The  reward is unobstructed views of Chicago from the  building's west side and a heart-stopping vista of the street and Chicago River below - for  those brave enough to look  straight down.  'It's like walking on ice,' visitor Margaret Kemp from  Bishop,  California said. 'The first step you take you  think "Am I going  down?"'
 
Long  way up: Even the floor of the platforms are glass - few were
Brave  enough to look straight  down.     
Fearless: Anna Kane, five, spreads out on the floor of the 10ft square box which is 1,353ft up.
Spectacular: She also enjoyed amazing views out across the city
Unfazed:  Although some adults felt dizzy after experiencing the Ledge,
Children  seemed to take it in their stride.
    
'At  first I was kind of afraid but I got used to it,' 10-year-old Adam Kane from  Alton , Illinois , said as clouds drifted by  below.    'Look at all those tiny things that are usually  huge.'   John Huston, one of the owners of the Sears Tower, even  admitted to
Getting 'a little queasy' the first time he ventured out on  to the balcony.   However, after 30 or 40 trips, he seems to have  gotten used to it. 
 
Thrill  seekers: The boxes jut out four feet from the building and were specifically  designed to make visitors feel as if they are floating    'The  Sears  Tower has always been about  superlatives - tallest,   larges t, most iconic,' he said.
'The  Ledge is the world's most awesome view, the world's most precipitous view, the  view with the most wow in the world.'    The balconies are  10ft high and 10ft wide, can hold five tons, and  have glass which is 1.5  inch thick.
  
Inspiration came from the hundreds of  forehead prints visitors left behind on Skydeck windows every week. Now, staff  will have a new glass surface to clean: floors.  
Architect  Ross Wimer said: 'We did studies that showed a four-foot-deep (1.2 metres)  enclosure makes you feel like you're floating since there's only room for one  row of people, not  two.'
The  Skydeck attracts 25,000 visitors on clear days. They each pay $15 to take an  elevator ride up to the 103rd floor of the 110-story office building that opened  in 1973
