Scotty's Castle is probably the biggest stop for tourists coming to Death Valley. It is well worth a visit, even several visits, for those coming to the park. I've personally been there countless times over the years, both just to walk around and explore the grounds, and also to go on one of the official tours. Currently there are two different official tours you can take at Scotty's Castle. The House Tour takes you inside the mansion to have a look at the rooms and learn about how Death Valley Scotty lived. It's very interesting, you learn a lot, and the staff does an excellent job in providing the tour and taking on characters from the past. The second tour is the Underground Mystery Tour, which literally takes you underground into the tunnels to see how the mansion was operated, including a look at how power was provided to the buildings through existing technology.  I'm not going to explain the history of Scotty's Castle, you can learn about that if you go. But keep in mind that there were four things that Death Valley Scotty lived by-- (1) Don't say nothing that will hurt anybody, (2) Don't give advice, nobody will take it anyway, (3) Don't complain & (4)Don't explain.