the adventure of the haunted cemetery

So, a certain Anonymous Commenter and I were hanging out on Saturday, and we happened to drive past a cemetery. Now this cemetery is small, fairly well-kept, and out of the way. However, it features an intriguing stone grotto complete with a tower on the top of a hill. I've wanted to go there since the first time I saw it, so we stopped. At the bottom of the hill is a handpainted sign that says "Rattlesnakes." Whatever. There are rattlesnakes around here if someone is foolish enough to go poking in holes in abandoned hillsides. We'd be fine.

We walked about halfway up the hill, Mr. A-C ahead of me by a few feet, when I saw this: I said in a calm and firm voice, "Mister Anonymous Commentator," and started running down the hill. When he turned around and said, "what?" I replied, "umm... there's a snake." He yelled and ran down the path a few yards. Then, out of some sort of masculine curiosity, turned back to get a closer look. That's when he found the OTHER one. We left in a hurry. Sandles aren't conducive to rattlesnake hunting.

Now, of course, my curiosity is piqued. Why are the rattlesnakes guarding the grotto? Is there some sort of treasure or mystery there? I need to get me some cowboy boots and a shotgun.