Teotihuacan

The pyramid of the moon located in Teotihuacán.

High on a plateau in central Mexico lies the remains of a city that continues to perplex archaeologists and historians. Of all the ancient cities of the Americas, Teotihaucan is the most enigmatic. Nobody knows what race of people built it, what they used it for, or why it was abandoned.

Tunguska Explosion

Vast areas were flattened by a meteorite in Tunguska in 1908. Leonid Kulik

It was just after seven in the morning on June 30, 1908, when something extraordinary happened above the remote wilds of Siberia. A colossal explosion ripped through the atmosphere five miles above the earth, unleashing chaos below.