Luray Caverns is in western Virginia not far from I-81's New Market exit. I've been there and it's quite awesome.
The caverns have some spectacular formations including the world's largest musical instrument called the "Great Stalacpipe Organ." There is an underground lake and some enormous chambers with ceilings as high as 10 stories. The image in the upper left of this post is the Great Hall.
If you can't get there to see these caverns in person, you can view some of the grandeur online. Luray has an excellent web site with lots of information on the science of cave formation. On their kids' activities page you can download coloring pages and mazes, and there is even an interactive CAVE QUIZ you can take.
Maddy
