<http://schema.org/alternativeHeadline>
"A collection of tunnels that have been used as bomb shelters, mushroom farms and sewers have caused over 200 buildings to collapse since 2011."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/lifestyle/responsible-living/stories/how-secret-tunnels-could-cause-rome-to-sink>