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 jut out four feet from the building's Sky deck.

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
got 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, largest, 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.