The Natural Bridge tour begins in the sinkhole that is the entrance to the cave. It was there that I and my fellow tourists met Brandon, our guide for the afternoon. He explained that the spot where we were standing was once a complete room that collapsed long ago, leaving the arch above. It's that arch for which the attraction is named. We also got a basic rundown of the cave's statistics: It was discovered in 1960; the tour is approximately 75 minutes long; the year-round temperature inside the cave is 70 degrees with a humidity level of 99 percent. (One more percent and we'd have been underwater.) Then it was on to some street-shoe spelunking.

We entered through a set of glass doors that had been installed years ago to maintain the aforementioned humidity level. And let me tell you, they do their job. The high humidity made the 70 degrees feel amazingly hot.

I shouldn't complain too much, though — the bats who used to live in the cave had a little more to worry about. As Brandon explained with the proper level of remorse in his voice, the bats who weren't inside when the doors were added were blocked out and left homeless. Those who were at home died of starvation. An almost undetectable moment of silence passed before Brandon snapped back into upbeat tour mode and moved on.

He led us down a winding path and deep into the cave, pointing out unique formations along the way: flowstone, "fried egg" stalagmites, unusually slender columns. But, one particular formation caught my eye; it was what appeared to be a largish mound of bare, black stone. Brandon mentioned that it was one feature we were allowed to touch if we wanted to, but the devilish gleam in his eye gave me pause. And a good thing it did, too. That black stone turned out to be a 3-to-4-foot-deep pile of bat guano. If you don't know what guano is, let's just say it's what happens to thousands of pounds of bugs when the bats are done with them.

Rounding Mt. Guano, we made our way into the Castle of the White Giants. The Castle is where the largest formations reside, including an enormous column named the Watchtower, which rises 50 feet from the floor to the ceiling. A testament to what time, hard water and a pretty nasty leak can accomplish before the invention of caulk.

Having witnessed such monumental shapes, I could feel the tour coming to an end. A welcome feeling, certainly, as I would soon be able to wring out my T-shirt and welcome the cool, 90-degree outdoor atmosphere. However, the best was yet to come.

We made our way up a steep incline and turned to look out over the Hall of the Mountain King. It is the largest room in the cavern and, in my opinion, the most spectacular view in the place. It's more than 100 feet wide, 100 feet tall and 350 feet long, and is filled with hundreds of formations that play tricks with the eye's perception of scale, making it difficult to tell just exactly how large a view you're witnessing. It certainly made an excellent finale to the tour.

On the way out, Brandon invited us to top off our visit to the caverns with a sip from the water fountain, which boasts genuine "cavern water." He said it's "straight out of the cavern" and is "just like bottled water or well water." A few visitors took him up on the offer, but I thought I would pass. After all, I prefer my bottled water not to be run through a four-foot bat-crap filter.