1. The Grand Canyon Skywalk
The glass bridge which is suspended 4,000 feet above
the Colorado River
on the very edge of the Grand Canyon.
The construction began in March of On May 2005, the final
test was conducted and the structure passed engineering requirements
by 400 percent, enabling it to withstand the weight of 71 fully loaded
Boeing 747 airplanes (more than 71 million pounds.)
The bridge is able to sustain winds in excess of 100 miles per hour
from 8 different directions, as well as an 8.0 magnitude earthquake
within 50 miles.
More than one million pounds of steel has gone into the construction of
the Grand Canyon Skywalk.

4. construction