On the 50th anniversary of its first flight, a history of the DC-3 illustrates its importance to aviation.

The experience of organ donation, including patients who need transplants and families who make the choice to donate organs of deceased family members; the critical shortage of organs; research into "organs by design."

The architectural design of Beijing's ancient complex of palaces and temples enabled it to survive centuries of earthquake shocks.

Design secrets that made chariots a war machine for hundreds of years; how they were used and how they helped unify China.

The March 11 earthquake, the worst to ever strike Japan, spawned a tsunami with 30-foot-high waves that destroyed entire towns in minutes.

Consistently stunning documentaries transport viewers to far-flung locations ranging from the torrid African plains to the chilly splendors of icy Antarctica. The show's primary focus is on animals and ecosystems around the world. A comic book based on the show, meant to be used an as educational tool for kids, was briefly distributed to museums and schools at no cost in the mid-2000s.

This award-winning series presents compelling untold stories and covers a wide array of provocative subjects. "Explorer" aired for 25 years -- the longest-running documentary series in cable TV history -- before being relaunched in 2015 after a five-year hiatus. Each monthly episode of the new "Explorer" takes a similar deep dive inside a story from the pages of a recent National Geographic magazine issue, taking viewers not only to the most remote corners of the globe but also to the furthest reaches of the mind and deepest crevices of history -- on urgent missions of discovery.

"Frontline" offers an unflinching and compelling look at complex, vital and often-controversial subjects. Each broadcast consists of a long-form news documentary. Topics run the gamut -- from Bernie Madoff's intricate fraud and prisoner abuse at Abu Ghraib, to AIDs, racial issues and Wal-Mart's effect on the U.S. economy.