Here are some contenders, based on different criteria:
* By volume: Mount Augustus, a monolith in Western Australia, is considered the largest rock in the world by volume. It's 850 meters tall and covers an area of 1,614 square kilometers. However, it's technically an inselberg, a large isolated rock formation, rather than a single rock.
* By height: Uluru (Ayers Rock) in Australia is the tallest monolith, reaching 348 meters high. It's a sacred site for the Aboriginal people and a popular tourist destination.
* By area: The Breadloaf in the U.S. state of California is the largest single, freestanding rock with a surface area of 190 acres.
Ultimately, it depends on your definition of "biggest" and "rock." There are many impressive rock formations around the world, each with their own unique features.
