<http://schema.org/alternativeHeadline>
"The mysterious, ancient caves are the star attraction of this Kentucky park, but 70 miles of above-ground hiking trails and 30 miles of paddling opportunities will bring you back for more."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/wilderness-resources/stories/mammoth-cave-national-park-a-users-guide>