What On Earth

Urban explorers head to Kazakhstan to investigate a bizarre industrial complex found in a vast, remote desert.

Analyze satellite scans that show structures forgotten by time. Spot a top secret Nazi base in Poland, a perplexing network of circles in California, foul sea sludge in Turkey, dinosaur-era spheres in an Asian desert, and a derelict Yemeni vessel.

A strange mound emerging from a Turkish hillside leads a journalist along a 2,000 year long trail of bloodshed and riches.

An aerial scanner uncovers the remains of a castle, wiped from history.

Travel to Sardinia to explore towering structures built by a long-lost civilization and ponder starlike shapes in the Philadelphia suburbs. Then see an aquatic military base in North Korea, an African ship graveyard, and strange craters across Tonga.

How are a series of triangular structures off the California coast connected to one of the most bizarre episodes in US military history?