The Devils Tower is a laccolithic butte made up of igneous rock. It is situated in the Bear Lodge Mountains, in Crook County, United States. The oldest rocks in the Devils Tower were from 225 to 195 million years ago.
Why it is special: The Devils Tower rises almost vertically above the Belle Fourche River, 867 feet from the base to the summit. It stands at a height of 5,112 feet above the sea level. There are almost 4,00,000 annual visitors to the Tower, of which 1% attempt to scale it with traditional climbing equipment. The rock was declared a National Monument in 1906.