Adventureland, Magic Kingdom
There are also several survey markers all over WDW. This one is located outside of 'The Land' at EPCOT. You can see the location of many other "Disney Benchmarks" at: http://www.wintertime.com/OH/GC/Disney/disneymarks.html.
The manhole cover below is from Disney's Hollywood Studios to the right of 'The Great Movie Ride' on the way to 'Walt Disney: One Man's Dream.'