Rattlesnake Mountain is a 3,531-foot ridge in Benton County, Washington, overlooking the Hanford nuclear site and ranking as the county’s second-highest point. Known to Native peoples of the Columbia Plateau as Lalíik, “land above the water,” it is sacred to several Native nations and may preserve evidence of the ancient Missoula Floods. In the 20th century, federal control transformed the mountain: the U.S. acquired it in 1943 for the Hanford project, later added a Nike Ajax missile base, and then established an observatory on the summit. By the 21st century, cultural sensitivity, scientific reuse, and disputes over public access had made it a place of overlapping meanings.