Assertion: mammoth cave | /r/HasProperty | the most extensive cave system
Facets:
value: in the world
type: LOCATION
value: with at least another 80 miles
type: OTHER
Source sentences:
text: Mammoth Cave is the most extensive cave system in the world, with over 285 miles (458 km) of surveyed cave passageways within the property (and at least another 80 miles [128 km] outside the property).