Secret Passages?

I'm sure many people know, but there are still many that don't know about the tunnels below the Magic Kingdom. Most guest don't care because they come to see what's on the surface. But back in the days when Walt was alive, the Magic Kingdom was built to reduce cost of building space. The network of tunnels is how the cast members and characters get around. How else did you think Mickey could be in one spot and then suddenly be in another spot. Actually there are multiple characters. Inside some of the buildings is office space or living quarters to, again, conserve space. I enjoyed using them as a cast member to beat the crowd sometimes. It was fun to go through doors that guests didn't know about, kind of like a secret passage. However, EPCOT, Disney Studios, and the Animal Kingdom were not built like that. Their "backstage" is hidden by a gate. Disney used billions of dollars by not following the same pattern as the Magic Kingdom.