The World's Largest "Sandbox"
Thanks to Paul Gessler for pointing this out.

Lewis Carroll on the EPISTEMOLOGY of representation:
"That's another thing we've learned from your Nation," said Mein Herr, "map-making. But we've carried it much further than you. What do you consider the largest map that would be really useful?"  
  "About six inches to the mile."
""Only six inches!"exclaimed Mein Herr. "We very soon got to six yards to the mile. Then we tried a hundred yards to the mile. And then came the grandest idea of all! We actually made a map of the country, on the scale of a mile to the mile!"  
  "Have you used it much?" I enquired.
"It has never been spread out, yet," said Mein Herr: "the farmers objected: they said it would cover the whole country, and shut out the sunlight! So we now use the country itself, as its own map, and I assure you it does nearly as well.  

The Ningxia 1:500 scale map in context.


The 40 x 66m playing field is completed.
Two closeups of the map.
The largest known 3d terrain model at the scale of 1:500 (3 yards to the mile)
situated near the town of Huangyangtan, 30km south of Ningxia, Ningxia Autonomous Region, China.
The map covers an area of 0.56 by 0.44 miles! Note that North is to the left!
In Google Earth fly to: 38°15'58.40"N, 105°57'01.33"E

The actual terrain in Tibet.
The actual terrain being modeled at Aksai Chin, Tibet (note the shape and arrangement of the lakes).
The actual area modeled is 350 by 200 miles. Note that North is to the left!
In Google Earth fly to: 33°36'39.33"N, 79°03'46.24"E

Google Translation:
"Today, the Army plans Meng: look at the Army Aviation is how to carry out sand table exercises COOL! COOL!"
The original in Chinese.

Discussion on Wikipedia.
The map area superimposed on three campuses.

3/22/2014
An area of DUKE KUNSHAN UNIVERSITY which is the same size as the Ningxia terrain model.
Actual areas is 0.56 by 0.44 miles.
An area of DUKE DURHAM UNIVERSITY which is the same size as the Ningxia terrain model.
Actual areas is 0.56 by 0.44 miles.
An area of UCLA which is the same size as the Ningxia terrain model.
Actual areas is 0.56 by 0.44 miles.