Pretty fascinating place for a lot of the reasons already written about. I simply went here because I was curious and it was so easy to do on the way from Las Vegas to the Grand Canyon, and I am happy I did. The tour is well worth it, and is fairly priced at about $9. It is informative and surprisingly fast, but it gives you a nice overview and a lot of details as well. Plus you can get way down into the damn and understand how it works and how it was designed which gives a better appreciation of it.
I wish I had had more time to be able to more fully look at the museum, as it seems like a lot of care was put into it, and it was very well done from what I saw. Being able to look at it though was a fascinating sight though, and the pictures of it really don't do it much justice. The fact that it was manmade just adds a lot of the fascination...at least to me.
I've been to Las Vegas several times, but have only went to the Hoover Dam once. I can almost guarantee that the next time I go to Las Vegas, I will definitely go to the Hoover Dam. I would like to spend more time and read more and attempt to more fully contemplate what a remarkable achievement this dam is.