Castalian Springs is an unincorporated community and census-designated place (CDP) in Sumner County,Tennessee, United States. As of the 2010 census, its population was 556.
During the Mississippian culture period of prehistory, the Castalian Springs Mound Site was a major local earthwork mound center, built and occupied from about 950 into the 14th century. The Native Americans who built and occupied the complex site preceded the historic tribes later known to European-American settlers in the area. This was one of the sites constructed throughout the Mississippi Valley and its tributaries, connecting regions from the Great Lakes to the Gulf of Mexico. The site was first excavated in the 1890s. It was excavated professionally in the 2005 to 2010 archaeological field school led by Dr. Kevin E. Smith from the University of Alabama. A number of important finds have been associated with the site, most particularly several examples of Mississippian stone statuary and the "Castalian Springs shell gorget," now held by the National Museum of the American Indian.