CIA @CIA
Answer: Mammoth Cave, in west-central Kentucky, is the world's longest known cave system with 405+ miles of surveyed passageways; nearly 2x as long as the 2nd-longest cave system, the Sac Actun underwater cave in Mexico. #CIAWorldFactbook #FIFAWWC https://t.co/LFwU4au0Hr — PolitiTweet.org