Braidwood is a city in Will County, Illinois, United States, approximately 53 miles (85 km) southwest of Chicago and 18 miles (29 km) south of Joliet. The population was 5,203 at the 2000 census. The Braidwood Nuclear Generating Station, a nuclear power plant currently owned by Exelon Corporation, is also located in the area (although the plant's address is actually in the nearby town of Braceville).
The Son Doong Cave in Vietnam is the biggest cave in the world. It's over 5.5 miles long, has a jungle and river, and could fit a 40-story skyscraper within its walls. But nobody knew any of that until about six years ago.
It is centered on the Green River, with a tributary, the Nolin River, feeding into the Green just inside the park. With 405 miles (652 km) of surveyed passageways Mammoth Cave is by far the world's longest known cave system, being over twice as long as the second-longest cave system, Mexico's Sac Actun underwater cave.