The Baigong Pipes
The account
Iron pipes inside a mountain are said to be the remains of an alien base thousands of years old.
What investigators found
Geologists explain the structures as natural casts of tree roots mineralized with iron.
The story
Near Lake Toson, in Qinghai Province in western China, a small mountain called Baigong displays structures that look like rusty pipes protruding from the rock and sand. In the early 2000s, Chinese news reports and popular books claimed they were the plumbing of an ancient alien launch base, tens of thousands of years old.
The story spread across the Western internet as proof of lost technology. Scientists who studied the site proposed a natural explanation: tree roots buried in sediment decomposed, and the empty spaces were filled by iron-rich minerals, creating cylindrical casts. Similar structures exist in other parts of the world. The site continues to attract the curious, but shows no sign of artificial origin.