I spent almost 2 hours in there and didn't realize it. This place covers the history of the Nevada Test Site and also the history of atomic testing in general. It's interesting and you learn things like the casinos used to promote watching tests from their roofs in the 1950s. They have old films from the 50s and 60s on what to do in the event of an attack,  items used in nuclear testing/weapons, etc. Interesting stuff and check out the ground zero theater to get an idea of what it was like to view a nuclear test.  There is a lot of reading of the signs to see what stuff is and if you are not a techie you will probably breeze through the last part pretty quickly. \n\nI printed a $2 off coupon off of their website. Also the vending machine in the lobby has $1 water, Gatorade, etc. that you might need if you walk there in the Vegas heat.