National Geographic celebrates the 25th anniversary of Explorer, the longest running documentary series in cable television history, with a commemorative special. Explorer has taken viewers to more than 120 countries, opening a window on hidden parts of the world, unlocking mysteries both ancient and modern, and investigating amazing and powerful stories of science, wildlife, and human nature. Hosted by Lisa Ling, the 25th anniversary special looks back at how the world has changed in a quarter century and how the award-winning Explorer series has chronicled our changing world. Highlights include Search for the Afghan Girl and Africa Extreme.