Location: You can find the icon on our map by looking in western Egypt (here is the map).
Sea of sand
"Big Cairn" is a famous landmark in Egypt's Great Sand Sea.
Why It's Interesting
Desert explorers in the 1930's and Allied military during WW II navigated in this featureless desert by dead reckoning and star sightings. The known location of this rock cairn was one of the few features (man-made of course) they could use to correct for accumulated navigation errors.