What's this hole thing about.....

On the way home today I saw some one digging a hole with heavy machinery. I didn't think much of it other than the fact that it had 1 guy operating the machine and about 7 guys just looking into the hole. Ever notice when you see a hole in the ground, wall, your head, you just have to stop and look in it? Maybe it's something that humans are drawn to. I am not quite sure, but hell if a hole isn't damn fucking interesting to look down.