'More than 350 miles of passages have been mapped in <a href="http://www.j-archive.com/media/2007-05-08_J_09.jpg" target="_blank">this</a> longest cave'
Mammoth Cave
WONDERS OF AMERICA STAMPS: More than 350 miles of passages have been mapped in this longest cave
More than 350 miles of passages have been mapped in this longest cave
More than 350 miles of passages have been mapped in this longest cave
WONDERS OF AMERICA STAMPS
Mammoth Cave
WONDERS OF AMERICA STAMPS