It's worth sitting through the annoying "in a world..." narration to see the structure of an immense colony of ants. The scientists poured 10 tons of concrete down into an abandoned ant colony, waited for it to harden, and then spent weeks excavating the results.
During the construction of the giant structure, it's estimated that the ants hauled 40 tons of dirt out of the holes, the equivalent of building the Great Wall of China. (via cyn-c)
Update: The ant colony was not abandoned. Nice work, scientists!