<http://schema.org/description>
"The World Trade Center slurry wall survived the September 11 attacks to become an iconic reminder of a nation&amp;#039;s loss and resolve. Test your knowledge of this unique structure with our quiz."^^<http://www.w3.org/2001/XMLSchema#string>
<http://science.howstuffworks.com/engineering/structural/world-trade-center-slurry-wall-quiz5.htm>