Devil's Postpile is a natural geological formation located in California, near Mammoth Mountain. It features unique columns of basalt rock that were formed by volcanic activity around 100,000 years ago. The columns are stacked in a striking, vertical arrangement, creating a visually stunning landscape. The site is part of the Devil's Postpile National Monument, established in 1911 to protect its geological features and surrounding wilderness. Visitors can explore the area through various hiking trails, including a popular route to the top of the postpile, where they can enjoy panoramic views of the Sierra Nevada mountains.