In the southern part of Britain, just a little bit north of Stonehenge and northeast of the massive Avebury stone circles just off Dragon Hill Road on White Horse Hill there is a famous relic from the bronze age, about 1,000 B.C. In Google Earth look at 51.578920,-1.568262
For some reason the Celts dug away the top soil (thus exposing the chalk underlaying it) and made a beautiful abstract modern-art image of a horse. The horse is really big, measuring in at 110 meters long (374 feet).
In fact there are many other white horses both in Wiltshire, UK and even a few abroad.
Without any doubt the most famous white horse is this one at Uffington.
The largest one anywhere in the world is the one painted on the desert mountain in the southwest part of Juarez, Mexico just a few kilometers away from El Paso, Texas.
The local architect Hector Garcia Acosta has made a copy of the reverse image of this famous Uffington horse using whitewash. This one in Mexico is 960 meters long, or more than a half-mile long.
In Google Earth look at 31.662032,-106.588063