In 1811, an anonymous man stood in awe of the giant cave chamber now called Rotunda, 141 feet beneath your feet. The chamber's huge size inspired him to call the whole cave "the Mammoth Cave." The name stuck.
The chamber itself, originally called the Big Room, became known as the Rotunda for its round ceiling.
Rotunda is the sixth largest room in Mammoth Cave, roughly 140 feet wide and 40 feet from floor to ceiling.