Engineering the Impossible (National Geographic Channel)

In a segment focusing on the Colosseum, experts explain how pioneering Roman engineers designed a drainage system that diverted an entire lake to make way for the amphitheater. To overcome the issue of the building's weight being unable to support itself, they pioneered the use of structural arches and invented concrete and red bricks. Finally, they kept the project on schedule by streamlining the materials' production process.

For both history buffs and building connoisseurs, Engineering the Impossible is an enjoyable blend of curiosity and education. But its most impressive accomplishment is making what could be a pretty dull topic entertaining enough that casual viewers will get something out of it, too. And there's virtually no worrisome content here, so if your tweens are so inclined, encourage them tune in.