"California Cavern located... in Calaveras County has been open to the public since 1850 and was California's first show cave. Early visitors included Bret Harte, Mark Twain and John Muir who wrote about his visit in his 1894 book "The Mountains of California." For 150 years, visitors have enjoyed the unique delicate beauty of the cavern's crystalline formations. Some speleothems, such as the beaded helictites found in the Middle Earth area are very rare. Others are so numerous as to be spectacular, such as the "Jungle Room's" array of stalactites."