Less than 40 minutes from the Strip.. is a nice break from the land of casinos. You can take a tour or not. My typical modus operandi is to drive somewhere and hike in. I'm cheap. Amazing 1930s engineering technology went creating this structure.
It's hard to fathom how big this place is, how much earth was moved, how all our electrical outlet in North America end up at this place and how many workers must have died and remain entombed within its cement walls. Loved the experience!
Parking is covered and just a short walk to the visitor center. There are a couple of tours, neither of which I took. I just wanted to leave sin-city for a bit.