The Lascaux Cave
In 1940, a group of French teenagers were exploring the forests near Montignac when their dog started sniffing for something unfamiliar. After upheaving a loose stone shaft, they discovered an underground cavern with massive painted walls. They explored the cave in secret first, and then reported what they'd found to historians who determined that the cave paintings were between 15,000-17,000 years old...
Xian Terra Cotta Army
In 1974, a group of Chinese farmers happened upon an incredible discovery: the tomb of the first emperor of China's Qin Dynasty. The farmers were digging a well when one of their shovels struck something in the dirt. Later on when archaeologists took a closer look, they discovered around 8,000 life-sized terra cotta soldiers from 3rd century B.C...